Mistakes in-the Harry Potter Books

elow is a list of mistakes that occur in the Harry Potter book series, such as factual errors, plot holes and typos. Some of these mistakes were fixed in later editions of the same book.Differences between editions of the books
==General==
===Hogwarts===
*Although Hogwarts's full name is Hogwarts School of Witchcraft and Wizardry, a distinction between "witchcraft" and "wizardry" has never been made, and the two seem to be just synonymous with the much more used term magic. 
**However, there is a distinction between wizards and witches, which refers solely to their gender; thus, it is possible that "witchcraft" is magic performed by witches and "wizardry" is magic performed by wizards. They still suggest "magic" without implying any actual difference between them, but it is possible this was meant to suggest inclusivity.
**It is also possible that this is simply a case of synonymia, done for rhetorical effect; after all, "Hogwarts School of Magic" just doesn't have the same ring.
*Although Hogwarts is said to have a reputation as one of the safest locations in the wizarding world, dangerous events happened with a relative frequency at the school during Harry's years. These included the troll roaming the dungeons in the first year, the Serpent of Slytherin's attacks on Muggle-borns in the second year, a Dementor attacking the Hogwarts Express in the third year, the Triwizard Tournament in the fourth year, and several events relating to the Second Wizarding War in later years. Also, Voldemort followers such as Quirinus Quirrell, Peter Pettigrew, and Barty Crouch Junior all resided in the school for long periods in disguise (or, in Quirrell's case, concealing their true intents), which also posed a significant danger to everyone, especially Harry Potter.
*J. K. Rowling said in an interview that there are about one thousand students attending Hogwarts at any given time. However the books mention no more than five students of the same gender, House and year (for example, Harry is known to share a dormitory with only four other boys: Ron, Neville, Dean and Seamus). If this pattern is consistent across the whole school (5 boys and 5 girls per house per year), there would be a total of only around 280 students. If a total of a thousand students was equally divided, each dormitory per house per year would have about 17 to 18 boys or girls. 
**One theory is that Harry's year was an unusually small intake, due to the fact that the time at which those students would've been conceived was during the height of the First Wizarding War and many wizarding families may have been reluctant to bring children into the world at such a dangerous time.
**It is also possible that there are more dormitories that don't appear in the books and films. The only ones mentioned in the books are the ones that house the students who are actually in the book, e.g. Harry, Ron, Neville, Hermione.
===Date of Albus Dumbledore's death===
*According to Pottermore, 30 June 1997 was the date Albus Dumbledore died and, by extension, the date the Battle of the Astronomy Tower occurred.Albus Dumbledore Fact file at (via the Internet Archive) However, several statements spanning and make this date impossible:
:*Immediately before Harry receives Dumbledore's summons to accompany him on the Skirmish at the Cave (therefore, this was the very night Dumbledore died), Harry says he'll be doing detention that Saturday and the two Saturdays afterwards, meaning there's at least 2-3 weeks until the end of the school year, the date of which is firmly established in previous books to be around 30 June. This places the date of the skirmish and the Battle of the Astronomy Tower (and therefore Dumbledore's death) sometime in early-to-mid June. There's also nothing to suggest that it was the last day of term, and the early-to-mid June timeframe also fits in with the O.W.L and N.E.W.T exams that were happening at the time.
:*The end of the year is stated to have happened a few chapters later, in The White Tomb.
:*The school year cannot have run into July, as Harry is stated to have been at 4 Privet Drive for at least four weeks as of 27 July. This means the school year ended at the end of June as normal. It is also known that there would have been at the very least a few days between Dumbledore's death and his funeral (and, in all likelihood, longer than that, as Dumbledore was such a high-profile person), after which the students were sent home.
:*All lessons and exams were cancelled or postponed due to his death, meaning the school year was ongoing.
:*When Rufus Scrimgeour came to carry out Dumbledore's will on Harry's birthday (31 July), Harry states that Dumbledore died more than a month ago, which means it would have been before 30 June, and even if 'a month' is taken to mean exactly 28 days, it still doesn't necessarily place it at 30 June; it could be any date before 3 July. 30 June, however, would contradict the above-mentioned statement about Harry being away from Hogwarts for at least four weeks (28 days) as of 27 July, as the students had gone home by then (30 June). In the same scene, it was stated that the 31 days (a month, in the sense of the same date in successive months, or in this case as close as possible) for the Decree for Justifiable Confiscation ended on that day, meaning its triggering cannot have coincided with Dumbledore's death (this is the logic used for the 30 June date; it assumes the two happened at the same time, which there's no evidence of), but would have been some time afterwards, presumably when his will was found or when the Ministry seized the items. It is known that wills can take time to be found, as Sirius Black's will wasn't found until early July 1996, even though he died in the middle of June.
:*The Daily Prophet article DUMBLEDORE – THE TRUTH AT LAST?, published on 27 July, mentions that the book The Life and Lies of Albus Dumbledore was completed four weeks after Dumbledore's death. This is sometimes taken to mean 27 July was the completion date for the book, which indeed leads back to 30 June being the date Dumbledore died. However, the article does not actually say this, just that the book was completed four weeks after his death. In fact, the context seems to suggest the book was completed before the article was written, which places the date of Dumbedore's death before 30 June.
===Other===
*The books mention several weekdays as having fallen on specific dates (which are either stated directly or known indirectly). However, many of them do not match the actual dates in real life. In particular, the day after the Start-of-Term Feast (i.e. 2 September) seems to be a Monday every year. A possible explanation is a slight calendar difference, either in-universe between the wizarding and Muggle worlds, or between the book world and the real world.
*Much is made of Hagrid's innocence of attacking Muggle-borns, both from his time as a student and when he was taken to Azkaban as a precaution, but there were several offences that he should in fact have been charged with and wasn't, such as keeping a dragon as a pet, endangering students with some of the creatures in his class and breeding the Blast-Ended Skrewts.
*The purchasing power of wizarding currency is incredibly inconsistent throughout the series. In the Chamber of Secrets, Molly Weasley is able to purchase supplies for all five of her school age children for one Galleon and 'a very small pile of silver Sickles', but in the Half-Blood Prince a copy of Advanced Potion-Making alone costs 9 Galleons. Furthermore, based on the prices on the Fantastic Beasts and Where to Find Them and Quidditch Through the Ages companion books, this would put the price of the potion book as nearly £45, which seems a lot for a mandatory secondary school textbook. (Although this may also be due to the fact that the book is likely to be imported from Brazil and later translated into English, since the author Libatius Borage, a famous South American potioneer, is a known alumnus of Castelobruxo.)
**Another explanation could be : the prices of wizarding goods could have increased after the Return of Lord Voldemort was publicly acknowledged.
====
===Cover===
*The art for the cover of the original UK edition depicts Harry at Platform Nine and Three-Quarters wearing a Gryffindor scarf. However, Harry hasn't been sorted yet. It is possible, however, that the illustration is of Harry returning to Little Whinging at the end of the school term (although given the look of surprise on Harry's face, this is unlikely as his expression would be more appropriate to seeing the train for the first time). Another explanation could be that this was the result of a coincidence in which he already owned a red and gold scarf at the Dursleys' house before starting at Hogwarts.
*The cover art of the original UK edition depicts another train beside the Hogwarts Express. The train, which is meant to be an InterCity 125, is at a platform that High Speed Trains do not use, but does accurately depict the InterCity Swallow livery of the era.
*The Bloomsbury Original Adult Edition cover depicts the Hogwarts Express as a Norfolk & Western J class (specifically #602), a class of streamlined steam locomotives that was used in the United States and would be too large for the British loading gauge.
===Chapter 1: The Boy Who Lived===
*The beginning of the story takes place on a "dull, grey Tuesday." But in 1981, 1 November was on a Sunday.
*The Muggle news reports an unusually large number of owls awake and flying around in the daytime. However, no mention is made that the owls are carrying packages or letters, which is the only reason so many of them would be out and about during daylight, and for that matter, would make for a much stranger (and therefore newsworthy) sighting by Muggle standards than just the fact that the owls are awake during the day.
*It is very unclear how much time goes by between certain events on 31 October and 1 November. Sirius arrived on the scene at Godric's Hollow the night James and Lily died, and Hagrid arrived there a short while later. When Hagrid picks up Harry from Godric's Hollow early in the morning "right before the Muggles started swarmin' around" he borrows Sirius' motorbike. However, Hagrid arrives on the motorbike late to Privet Drive when it is "nearly midnight" the next day, having not spoken to Dumbledore since he went to go pick Harry up. As the chapter depicts a whole day between when James and Lily died and when Hagrid arrives at Privet Drive, Hagrid and Harry are missing, or unaccounted for, for nearly 24 hours.
*It is unknown why Professor McGonagall was staying next to the Dursleys' home all day, instead of being at Hogwarts, tending to her duties as transfiguration teacher and head of Gryffindor House. It is highly unlikely that she was stationed there on Dumbledore's orders, as Dumbledore was surprised to see her there. It is also equally unlikely that she was there to see Harry be delivered to the Dursleys, as she was surprised and appalled when Dumbledore announced his intention to do that. The only thing she knew (as she heard this from Hagrid) was that Dumbledore was planning on going there, but she has no reason to keep tabs on Dumbledore, especially at the expense of her duties at Hogwarts.
**It is possible that, similar to when exams were cancelled as a school treat (amid celebrations) after the Serpent of Slytherin was slain in the Chamber of Secrets, the students and staff of Hogwarts were given the day off to celebrate (indeed, Dumbledore was surprised, not that McGonagall had been away from Hogwarts, but that she hadn't been celebrating). Given McGonagall's disapproval of the gaieties across the wizarding world, it seems that she had no desire to participate in them, so she just waited for him where she knew he was going to be.
*Dumbledore says that he passed through several parties to get to Little Whinging, even though he apparently got there by Apparition, a direct form of transport, judging from his sudden appearance next to Minerva McGonagall. He could have Apparated several times to go to many parties – possibly in order to lose anyone (such as Death Eaters) who might have been following him. It is also possible he walked or flew most of the way, and only decided to Apparate a very short distance to Privet Drive, though what motive he would have for this is unknown.
*In the Bloomsbury edition, on page 17, Hagrid says "I'll be takin' Sirius his bike back"; yet, in , Sirius told Hagrid to keep the bike because he didn't need it anymore. It is, of course, possible that Hagrid intended to give the bike back in spite of his friend's protests, feeling Sirius may not have meant it. Still, in later editions of this book, the problem was fixed by having Hagrid say "I'd best get this bike away" instead.
*When Dumbledore tells McGonagall why he's bringing Harry to the Dursleys, he tells her that Harry won't remember the attack. However, in , Harry relives it when near a Dementor, meaning that he did remember it, even if his memory needed jogging.
**Dumbledore could simply have been mistaken in assuming Harry wouldn't remember it.
**Another possibility is that he was just saying that in order to make his reason seem more credible to McGonagall, as it is revealed in that this wasn't the real reason. This is further supported by the fact that, as Dumbledore explained to Harry in the same scene and contrary to what Dumbledore told McGonagall here, he did in fact know how Harry survived, so Dumbledore wasn't being entirely truthful to McGonagall anyway.
===Chapter 2: The Vanishing Glass===
*Piers Polkiss is described as "a scrawny boy with a face like a rat", but in another part of the book Dudley's gang is described as all being "big and stupid" with Dudley being the biggest and stupidest.
**Possibly he was scrawny compared to the other gang members but still large compared to Harry who, at that time, was described as "small and skinny".
*The trip to the zoo is said to take place on a Saturday, but Dudley's eleventh birthday (23 June, 1991) was actually on a Sunday.
*The boa constrictor at the zoo supposedly winked at Harry during their conversation. As snakes don't have eyelids in real life, it is impossible for them to wink. The snake may have been magical or have instead contracted its facial muscles around its eyes to appear to wink, though the possibility of even this is debatable. It is also possible, if unlikely, that snakes in the Harry Potter universe are slightly different from their real-world counterparts, which would go along with their apparent higher intelligence.
===Chapter 3: The Letters from No One===
*Harry's 11th birthday (31 July, 1991) was said to be on a Tuesday. But in 1991 in the real world, that date was a Wednesday.
*On page 31, the sentence "Harry could see Uncle Vernon's shiny black shoes pacing up and down the kitchen" begins with a speech mark, even though the line is not being spoken by anyone. It is amended in later editions.
===Chapter 4: The Keeper of the Keys===
*Hagrid tells Harry that "There's not a witch or wizard who went bad who wasn't in Slytherin." However, Peter Pettigrew betrayed Harry's parents and he was in Gryffindor. While Hagrid didn't know at the time that Pettigrew was the traitor, he did believe that Sirius was and he was also a Gryffindor, so Hagrid's statement is incorrect from either perspective.
===Chapter 5: Diagon Alley===
*On Harry's Hogwarts list of school supplies, "1 Wand" is listed twice, as both the first and last item on the list. This mistake was fixed in later editions of the book. The list of school supplies also doesn't include potion ingredients, although Harry later buys them. In later editions of the book this has been corrected.
*Harry buys the book One Thousand Magical Herbs and Fungi, but later, he looks up dittany in "One Hundred Magical Herbs and Fungi". This error was, however, amended in later editions.
*The air in the tunnels of the Gringotts vaults is described as getting colder when you go deeper into the earth. However, in theory, it should get hotter as you go deeper as once you get below a level where the temperature depends heavily on the weather at the surface, the geothermal gradient takes over and it gets hotter as you go deeper. Of course, there may be enchantments in place to account for this discrepancy.
*When Harry returns from Diagon Alley to Little Whinging, he takes a train from Paddington Station. However, Little Whinging is in Surrey, south of London, so he should have travelled from Victoria or Waterloo; trains from Paddington head to the west.
*Despite Garrick Ollivander's claims that the original Ollivander arrived to Great Britain with the Romans, this individual started his wand-making business in 382 B.C. but the Roman conquest of Britain (Britannia) only began effectively in A.D. 43, under Emperor Claudius. An earlier attempt was made in 55-54 B.C. by Julius Caesar, as an adjunct of his Gallic campaign. Prior to then, the Romans had only sporadic contact with Britain, to the point where, up until 124 B.C., many Romans did not believe the land actually existed.
===Chapter 6: The Journey from Platform Nine and Three-Quarters===
*Aunt Petunia is described as looking as surprised as the other Dursleys about Harry needing to board at Platform Nine and Three-Quarters, yet according to , she had been there at least once. However, she may have been pretending to be startled in order to distance herself from the magical world.
*Mrs Weasley asks her children which platform the train departs from, but she should know this perfectly well, since she departed seven times from the same platform. However, it is possible she only asks so her children remember.
*On page 79, the closing quotation mark is missing right after Hermione tells Harry about the books he is in. This mistake was fixed in later editions of the book.
*King's Cross Station is described like St Pancras Station, instead of King’s Cross.
===Chapter 7: The Sorting Hat===
*None of the new students know beforehand what the Sorting Ceremony involves. While this makes sense for the Muggle-borns and Harry, as they had no knowledge of the wizarding world, it doesn't for those that have grown up in it. Even Ron has no idea, despite having two parents and five older brothers as current or former students, and it seems highly implausible that none of them ever mentioned it to him (other than Fred joking about wrestling a troll).
*While being sorted into houses, Harry looks up at the Sorting Hat's stool, and there are only three people left to be sorted. Professor McGonagall then calls out the names of four more students. This error only occurred in the US edition and was rectified in later editions – in the UK edition Dean Thomas's name is omitted.
*During the Sorting ceremony, Sally-Anne Perks is sorted before Harry but, , when everyone in fifth year are being called in alphabetical order to take their practical O.W.L.s, Parvati Patil is called before Harry. It should actually have been Sally-Anne Perks, but because many students were pulled out of the school that year, it is possible that Sally-Anne was cut out.
*When Harry first meets Nicholas de Mimsy-Porpington, the ghost says how he has not eaten in nearly 400 years. Yet he had, at the time, already been dead for 99 years longer than that. This was fixed in later editions of the book.
*It was stated in a previous chapter that Harry's birthday, 31 July, was on a Tuesday (regardless of what day it actually fell on in 1991), which would mean that 1 September was on a Saturday. The next day would have been a Sunday, yet classes began.
===Chapter 9: The Midnight Duel===
*Fred tells Harry that the Gryffindor Quidditch team hadn't won a championship "since Charlie left". Charlie attended Hogwarts from 1984-1991, and so had only just graduated as Harry arrived – Harry filled the seeker vacancy left by Charlie. It is a strange way to put it since no time had really passed since Charlie left, though Fred is still telling the truth as they hadn't won since 1986 which is when Charlie attended.
**It is possible Charlie, while still at school, had left the Quidditch team a few years before actually leaving Hogwarts, which would fit with Professor McGonagall expressing the need for a better team than the previous year.
===Chapter 10: Hallowe'en===
*During the Hallowe'en feast, when the troll is let in, Professor Dumbledore sends the students to their dormitories, but the troll is said to be in the dungeons, and that is also where the Slytherin dormitories are, meaning that Dumbledore has put them directly in harm's way by sending them there. The logical move would be for every student to stay in the Great Hall, do a roll call, and send teachers to go and look for missing students.
===Chapter 11: Quidditch===
*The narrator says that if Gryffindor won the first Quidditch match, they would pull into second place for the House Cup. However, in Prisoner of Azkaban, the Hogwarts Quidditch tournament appears to have its own cup, independent of the House Cup.
**It is possible that winning a Quidditch match gives points to the winning team's house.
===Chapter 13: The Mirror of Erised===
*Dumbledore tells Harry that the Mirror of Erised 'gives us neither knowledge nor truth'. However, it does in the sense that it shows the viewer their deepest desire, even if they don't know what it is, thus giving them that knowledge.
===Chapter 14: Norbert the Norwegian Ridgeback===
*The night Charlie's letter shows up at Hogwarts is said to be Wednesday at midnight. However, earlier in the book it is mentioned that Astronomy classes take place every Wednesday at midnight which means that they are presumably skipping class, and the other students should not be asleep. Later editions have changed the day of Charlie's visit to Saturday.
*Curiously, McGonagall takes fifty Points from Harry, Neville and Hermione for wandering around the halls at night, but she only takes twenty from Draco Malfoy for committing the same offence. Earlier in the book, she takes only five Points from Hermione for her allegedly going to fight a mountain troll on her own.
===Chapter 16: Through the Trapdoor===
*During the match against the giant chess set, Ron says "Well, Harry, you take the place of that bishop, and Hermione, you go next to him instead of that castle." Except the castle is next to the knight, not the bishop. It is possible though that when Ron said "next to him" he didn't mean immediately next to, only in the general area of where Harry was located.
*Also in the match, Harry was acting as the bishop. His last move was to move three spaces to the left. However, in real chess bishops can only move diagonally. However, it could also mean that Harry simply moved 3 spaces left diagonally, and wasn't written properly.
*At the beginning of the same match, Ron is the knight in the giant chess set. It later says that he had to "move ahead one" so that the Queen could take him, opening the path for Harry to checkmate the king, and win the match. If he were a knight, he would only be able to move either ahead one, and sideways two, or ahead two, and sideways one. It is possible, however, that "one" was meant as one move, rather than one space.
*When Harry and Hermione drink the two potions to get them through Snape's task, there is only one bottle to get them through the black fire and only one bottle to get them through the purple fire. The smallest bottle holds the potion for the black fire, and it only contains enough for one person. If this is so, then it is unknown how Quirrell got to the Mirror of Erised in the first place.
**Although, it's possible that the task just reappears again, just like the chess set was intact and Harry, Ron and Hermione had to play the game again.
**It is also possible that Quirrell had only taken a sip of the potion himself, therefore only leaving enough for one more person.
*If Dumbledore's letter from the Ministry really was urgent, it seems odd that he would choose to fly all the hundreds of miles there rather than get there almost instantly by Floo powder or Apparition (though the former had yet to be introduced). He could have done that and seen right away that it was a trick, so Quirrell and Voldemort's scheme to lure him away by falsifying business with the Ministry falls right apart.
===Chapter 17: The Man with Two Faces===
*Dumbledore says that he and Hermione's owl crossed in mid-air. However, a few pages later Hermione says to Harry that she ran into Dumbledore on the way to the Owlery to send him the owl.
**He actually says "We must have crossed in midair", indicating that he is making an assumption. Harry merely informed him of Hermione's intention to send an owl. Since Dumbledore is not omniscient (as he admits himself) the explanation he'd assumed for why he hadn't received it may have been wrong, as he didn't know she hadn't sent it.
*Dumbledore explains that only a person who wanted to find the Stone, but not use it, would be able to get it. However, by that logic, Quirrell should have been able to get the Stone without any problem, as he did not want to use the Stone himself, only present it to Voldemort.
**It's possible that the Mirror regarded Voldemort and Quirrell as a single person as they were inhabiting the same body.
**It's also possible that the Mirror knew that Quirrell wanted to give the Stone to Voldemort, which is still using it, just not on himself.
*If nobody could acquire the Stone if they wanted to use it, then it is unclear how Nicolas Flamel was supposed to get it in order to make more Elixir of Life. Perhaps he had already decided that he was ready to die and had no desire to have the Stone anymore, but then, why didn't he and Dumbledore just destroy the Stone as soon as it was retrieved from Gringotts?
**It is possible that Dumbledore would have lifted the spell if Flamel needed the Stone.
*It is unknown why Dumbledore and/or Flamel could not have used the Fidelius Charm to hide the stone and/or its whereabouts.
====
===Cover===
*The UK version of the cover illustration of Harry, Ron, and Hedwig in the flying Ford Anglia incorrectly depicts Hedwig as a barn owl rather than a snowy owl.
*On the front cover of the Spanish edition, Harry is holding the sword and looking at the Basilisk, but looking into a Basilisk's eye's is fatal, so, technically, Harry should be dead on the Spanish front cover. However with Fawkes having clawed out the Basilisk's eyes, Harry would be able to look on without fear of death.
===Chapter 2: Dobby's Warning===
*Petunia should have been aware that underage wizards and witches are not allowed to use magic outside of school, since the rule was written in 1875, well before Lily's time at Hogwarts. However, it could have been that Lily had simply forgotten to mention this to her. It should be noted that in book 1 during Harry's birthday, she claimed that Lily "turned teacups into rats".
*The Ministry of Magic detected Dobby using the Hover Charm and assumed it was Harry. However, by that logic, they should have also detected the Disapparition Spell performed immediately after the Hovering Charm, and realised that this spell was far above the paygrade of a second-year student.
*Sending an owl to deliver a letter, in the presence of two Muggles who did not know that wizards exist, ironically does far more to expose the existence of the wizarding world to Muggles than a spell that happened when those Muggles' backs were turned.
===Chapter 3: The Burrow===
*After Harry, Ron, Fred, and George arrive at the Burrow, Mrs Weasley shouts at Fred first. Then she says, "and you two" glaring at Ron and Fred, but it should say George since she has already yelled at Fred. This error was corrected in later editions of the book.
*In the US edition of the audiobook read by Jim Dale, Ginny's eyes are stated as being bright green but in the printed US first edition, and the UK version of the audiobook read by Stephen Fry, they are said to be bright brown, which agrees with the description in of Molly's eyes being the exact same shade of brown as Ginny's.
===Chapter 4: At Flourish and Blotts===
*The Hogwarts equipment list mentions the Lockhart book "Wanderings with Werewolves", but later, Lockhart refers to the book as "Weekend with a Werewolf". This error was fixed in later editions of the same book.
===Chapter 5: The Whomping Willow===
*When Harry and Ron arrive at Hogwarts in the flying Ford Anglia, a scene which takes place on 1 September, 1992, they are told that they had been seen by Muggles in various locations, including the "Post Office Tower". But due to a change of ownership, the tower has actually been called the BT Tower since 1984. Also, the building is about a mile southwest of King's Cross, so to pass it, Harry and Ron would have had to be going in an entirely different direction to be following the Hogwarts Express.
===Chapter 8: The Deathday Party===
*Harry, Ron and Hermione go to Nearly Headless Nick's 500th deathday party. However, in the first book at the start of term feast he says he has not eaten for nearly 400 years, which would imply that this is how long he has been dead.
**In later printings of the first book, Nick's comment is changed from "nearly 400 years" to "nearly 500 years".
===Chapter 9: The Writing on the Wall===
*Hermione says that Moaning Myrtle haunts the bathroom on the first floor. However, when Harry sees the writing on the wall outside her bathroom, he is on the second floor.
*It remains unknown how Moaning Myrtle never notices Ginny visiting her bathroom, or the pipe door opening, or the Basilisk coming through her bathroom.
**It is entirely possible that when the piece of Riddle's soul possessed Ginny, she temporarily gained some of his powers, likely including the ability to disillusion herself. She would have gained the ability to speak Parseltongue, or she wouldn't have been able to open the chamber. It is highly unlikely that Riddle would have got very far if he was limited to the abilities of a typical first-year.
**It is known that Myrtle does not spend all her time in the bathroom. It is therefore possible that Ginny/Riddle simply waited until she was away from the bathroom before opening the chamber. Riddle, being one of the world's most powerful wizards, presumably had some means of knowing whether she was there.
*Percy's name is once misspelled as Perry after he catches Harry, Ron and Hermione leaving Myrtle's bathroom.
===Chapter 11: The Duelling Club===
*When brewing the Polyjuice Potion, Hermione says that she should steal the ingredients from Snape's stores, rather than Harry or Ron, as they will be expelled if they're caught, whereas her record is clean. However, that isn't entirely true, because she claimed to have gone looking for the troll in their first year and lost five points for it, plus she was caught out of bed the night that she and Harry sent Norbert to Charlie.
**However, this might be related to the current school year, for which her record was actually clean. Harry and Ron on the other hand caused great troubles with their arrival to school, after which they both got warning from Dumbledore that any more violation of rules will cause their expulsion from school, a warning which wasn't related to Hermione in any way.
*When Harry speaks Parseltongue to the snake during his duel with Draco, everyone hears him hissing. Therefore, when Harry hears the Basilisk speaking in the walls, Ron and Hermione should hear hissing, yet they claim to hear nothing.
**A possible explanation for this could be that the Basilisk is hissing very quietly or is muffled by the pipes and the walls, so Ron and Hermione can barely hear it, but Harry can make out the words as he hears them in English.
===Chapter 13: The Very Secret Diary===
*When Harry is viewing the memory from Tom Riddle's diary, Tom Riddle says to Hagrid at one point, "The dead girl's parents will be here tomorrow." It is stated elsewhere in the book that Myrtle is Muggle-born. Muggles cannot enter Hogwarts. However, it is possible that an exception was made for them (the Muggle-Repelling Charm could be lifted a day or two, for this reason), or it could be that Tom simply assumed that Myrtle's parents were wizards (although this is highly unlikely, since it is later revealed that he was the heir of Slytherin, and thus had personally sought to bring about Myrtle's death, meaning he must have known that she was a Muggle-born). Another possibility is that he may have been bluffing in order to scare Hagrid.
*Valentine's Day in the book is depicted as a typical school day, albeit one where the cupid dressed dwarfs are interrupting classes. 14 February, 1993 was a Sunday, meaning there should have been no classes to interrupt.
===Chapter 14: Cornelius Fudge===
*When Harry is at the Quidditch pitch, after reflecting with relief that there will be no one in the castle to become victims of the monster of Slytherin, Professor McGonagall shows up to say that the monster has struck again, and that everyone should return to their common rooms. However, the students would have been far safer to remain at the pitch while the professors checked the castle again.
**It should be noted that, at the time, no one knew what the monster was or how it was attacking students; therefore, there was no reason to assume the students were safe outside (Harry was likely being naïve in assuming that, for he had no reason to think that at the time). The common rooms were presumably the students' default sanctuary, and it is likely they were sent there so they were together and the teachers knew where they were.
*It is written that "Harry had inherited just one thing from his father: a long and silvery Invisibility Cloak". This is untrue, as we find out in Chapter 5, Diagon Alley in , that Harry also inherited James and Lily's gold, kept at Gringotts.
**This is probably intended to mean that he only inherited one actual item, as opposed to a commodity such as money.
===Chapter 15: Aragog===
*When Harry tells Ron to be quiet or the 'something big' will hear them, Ron responds, "Hear *me*? It's already heard. Fang!" However the sentence should probably be "It's already heard Fang!" as it is read in the audiobooks. It is amended in later editions.
===Chapter 16: The Chamber of Secrets===
*It is stated that the Basilisk was able to move through the castle's pipes, but it remains unknown how something as large as the Basilisk would be able to fit through the plumbing.
**Based on the fact that Harry, Ron and Lockhart are able to move through the plumbing to get to the Chamber later on, it may be that the pipes for Hogwarts are simply that large, or may change shape depending on their load, just as the staircases can move.
*It is unclear how Fawkes spoke Parseltongue to enter the Chamber of Secrets to intercede Harry, nor how Ron could have been strong enough to help him get past the rubble caused by Lockhart's spell.
**It's likely that Fawkes simply Apparated past any barriers in his way, because it's known that phoenixes can disappear and reappear somewhere else naturally.
===Chapter 17: The Heir of Slytherin===
*Tom Riddle states that Lily Potter's death bought Harry "twelve years of borrowed time". This is incorrect as he had not yet turned thirteen, and Lily died when he was one, and so it should be "eleven years of borrowed time".
===Chapter 18: Dobby's Reward===
*On page 283 of some copies of both the US paperback and hardback editions, the word "professor" is misspelled as "professorr".
*Dumbledore tells Harry that Lord Voldemort is the last remaining ancestor of Salazar Slytherin. This is meant to say that Lord Voldemort is the last remaining descendant of Salazar Slytherin. 
**This error was fixed in later editions of the book.
*Dumbledore concedes that nobody will ever be able to prove that Lucius Malfoy slipped Tom Riddle's diary to Ginny before the start of term, let alone did so with the intention of opening the Chamber of Secrets; thus, Lucius could not be prosecuted. At the time Dumbledore says this, this is true. However, only a few minutes later, they suddenly have a witness they could have used against Malfoy: The newly freed Dobby! Bear in mind that, in Order of the Phoenix, Dumbledore offers to summon Dobby to give evidence in Harry's defence, and the Minister decided to accept Harry's version of events without needing the evidence. So clearly, house-elves are not considered incompetent witnesses by the Wizengamot.
====
===Chapter 1: The Dark Lord Ascending===
*With the death of Albus Dumbledore, Severus Snape should have become a secret-keeper for the location of 12 Grimmauld Place, and thus could have revealed that information to Voldemort. Perhaps Moody's Tongue-Tying Curse was keeping him from disclosing the information, but if that were the case, the casters of the Fidelius Charm could have used the curse more often to prevent the sort of treachery that led to Lily and James Potters' deaths.
**More likely he did become a secret-keeper, but hid this fact from the Death Eaters due to his true loyalty secretly being to Dumbledore, and since Voldemort did not know Dumbledore was the Secret Keeper, he wouldn't suspect Snape. It is also possible that Snape indeed told Voldemort, but the latter believed it was worthless to go there since the Order would have changed their headquarters.
===Chapter 2: In Memoriam===
*It is said that Harry never learned how to repair wounds, but he did learn at least one spell for such a purpose: Episkey, a spell which he even used at least once during Quidditch practice during Half-Blood Prince, Chapter 14 ("Felix Felicis"). Perhaps episkey is only for minor lacerations, but Harry moves past this cut on his hand just by running some water over it and administering some Muggle first aid. If it wasn't a minor laceration, he has no business ignoring it and should have called for an ambulance, and there is no indication that his otherwise untreated cut had impeded his wand hand for the rest of the book, or even that other characters even noticed it.
*It is said that Harry cannot use magic due to not coming of age for another four days. In chapter six, days have passed since the Battle over Little Whinging, but Harry states the Trace will break in four days.
===Chapter 4: The Seven Potters===
*As Harry is awaiting the Order, he reminisces about the few times as a boy he was left alone at Privet Drive as the Dursleys went out for fun, mentioning how he would often play on Dudley's computer and sneak tasty treats from the fridge. However, in , it is made clear that the Dursleys would never do anything of the sort, fearful that they would come back to find the house in ruins, instead opting to leave him with a babysitter (preferably Arabella Figg).
**It is possible that he was referring to summer holidays after he had found out he was a wizard, such as in the summer of 1994, when the Dursleys had significantly let up on their abuse of Harry out of fear of retaliation from Sirius. However, by that point, he would likely have had no interest in Muggle entertainment such as television or video games.
*Right before the Battle of the Seven Potters, Moody explains that the Ministry has restricted the use of Portkeys, Floo Network, or Apparition within the Dursley's house, which is why they had to resort to the elaborate "Seven Potters" ruse to get Harry to safety. However, this restriction only applied to the Dursley's home. They could have just placed a Portkey one foot outside the Dursley's lawn and had Harry jump to touch it, or have Harry grab Moody's arm and jump off the lawn at the count of three before undergoing side-along Apparition. Even if they absolutely had to use the "Seven Potters" ruse initially, the fourteen of them could have just disApparated - side-along or otherwise - the minute they took flight.
**They were still unable to use magic around Harry due to the Trace. However, as soon as the Death Eaters attacked, magic was being used all around Harry anyway, so why bother with the technicalities at that point?
*Couldn't Harry and Moody have simply walked together under the Invisibility Cloak a safe distance away from the Dursley's home (such as Mrs Figg's front yard) before undergoing side-along apparition?
**There are ways of detecting people under an Invisibility Cloak, as evidenced by the Marauder's Map. However, this raises the question of why such methods aren't used more often, such as when the trio appeared at the Hog's Head before the Battle of Hogwarts.
===Chapter 5: Fallen Warrior===
*Harry says 'What d'you mean? Isn't anyone else back?' but the first apostrophe is missing.
===Chapter 6: The Ghoul In Pyjamas===
*On page 78, Sept 2014 Edition. When Ron is explaining to Harry his plan to use the ghoul as a decoy Ron "with spattergroit", Rowling writes 'Harry merely looked his confusion'. This is presumably a typo / grammatical error as the sentence doesn't make sense. The most likely intended sentence is 'Harry merely looked with confusion'.
===Chapter 13: The Muggle-Born Registration Commission===
*Harry and Hermione call each other by their real names while freeing the Muggle-borns awaiting trial, rather than those of the people they are impersonating, which is sure to blow their cover.
**It is possible, given that they were freeing Muggle-borns, that they felt their cover had already been blown, and therefore didn't worry about it. However, this is unlikely, as Harry resumed impersonating Runcorn when he was challenged over freeing the Muggle-borns.
**Another possibility is that they didn't think it necessary to maintain their cover whilst in the presence of only the Muggle-borns, as it would have been fairly obvious they they were not who they appeared to be anyway.
**It is also possible that they panicked and momentarily forgot that they were under cover.
===Chapter 14: The Thief===
*Hermione is afraid to return to 12 Grimmauld Place for fear that she had inadvertently given the location to Yaxley. Harry theorises that Yaxley is also bringing other Death Eaters into the place. However, Yaxley should have been unable to do so, as only a secret-keeper can reveal a location hidden by the Fidelius Charm, and Yaxley would not have become a secret-keeper simply by learning a hidden location from another secret-keeper. He would only become a secret-keeper if the secret-keeper who reveals the secret to him (in this case, Hermione) actually dies.
**One possible explanation is that the Death Eaters may have deduced that, because Hermione was able to give the location to Yaxley, either she was the original secret-keeper (which is highly unlikely) or she is a second-generation secret-keeper, meaning the original secret-keeper was dead. Even if they didn't know that the original secret-keeper was Dumbledore, the fact that the original secret-keeper (whoever they may be) is dead necessarily means that Snape is now a secret-keeper as well, meaning Voldemort might have likely asked Snape to divulge the information, and Snape complied in order to maintain his cover.
*It is also a part of Fidelius Charm lore that a secret-keeper cannot be coerced into revealing the protected information; it must be divulged willingly. Therefore, Yaxley should not have been able to learn the secret simply by grabbing onto Hermione and not letting go, as this would not have been voluntary on Hermione's part.
**However, this could just be Harry and Hermione's speculation based on their limited knowledge on the Fidelius Charm.
===Chapter 15: The Goblin's Revenge===
*Ted Tonks uses Summoning Charm on a fish in the river by sayin 'Accio salmon' and it works. However it is said in the Book of Spells and Rowling's Official Site that 'Accio only works for inanimate objects'. A possible explanation is that the Summoning Charm merely causes irreparable harm to living things, such as turning their organs inside out, and since Ted and his friends were just planning on eating the salmon anyway, this wasn't a concern for him.
**In chapter 18 of Order of the Phoenix, Harry summons a bullfrog during a charms lesson, which proceeds to gloomily come back to him. Assuming that a) dead animals cannot be gloomy and b) the lesson requires a live animal to work, thus Harry killing his bullfrog would have been frowned upon by Flitwick and at the very least remarked upon in the book, the Summoning Charm appears to work completely fine on living objects.
**Why didn't Harry or Hermione or Ron think of using a summoning charm for anything they wanted to eat?
===Chapter 20: Xenophilius Lovegood===
*Ron explains that Voldemort had placed a Taboo on his name so that if anyone said it he would be able to find that person, and explains that was how the Death Eaters had found them on Tottenham Court Road — Hermione used the name once, while they were sitting in the cafe. However, the trio used Voldemort's name several times while they stayed at 12 Grimmauld Place, and the Death Eaters did not manage to find them there until Hermione accidentally brought one back with them, after Disapparating from the Ministry of Magic, although one or two strangers did appear near Grimmauld Place before with a dozen on September 1st. The charms placed on 12 Grimmauld Place which make the location impossible to enter unless invited but the jinx placed on Voldemort's name is specifically said to "break protective enchantments." However, it is highly likely that it may not be able to break the Fidelius Charm, which is notoriously strong.
*When Harry, Ron, and Hermione are at the front door of Lovegood House, Hermione says to Harry, "You better take off the Invisibility Cloak, Harry, it's you Mr Lovegood wants to help," and he handed her his Cloak to place in the beaded bag, but after the Death Eaters arrive Hermione says, "Harry give me the Invisibility Cloak, Ron, you're going to put it on."
===Chapter 23: Malfoy Manor===
*Narcissa says that Draco "is home for his Easter holidays." In the next chapter, the sun is described as rising at Shell Cottage in Cornwall, but shortly after this, Harry sees into Voldemort's mind at Hogsmeade, where it is "still dark, because it was so much farther north." However (in the absence of a significant longitudinal difference, as in this case), this sort of thing is only true between the Autumnal and Vernal Equinoxes; Easter occurs after the Vernal Equinox"Easter", The Calendar FAQ (e.g. on 12 April in 1998), in the other half of the year when sunrise is earlier the further north one goes, thus it should not have been dark at Hogwarts when Harry saw into Voldemort's mind.
===Chapter 25: Shell Cottage===
*Lupin says that Bill is the Cottage's Secret Keeper, yet Ron was able to tell Dobby about where the cottage was when escaping from Malfoy Manor. However, this is most likely because Ron was aware of the cottage's existence prior to the Fidelius Charm being placed on it, and thus was free to divulge the information on its whereabouts. However according to this logic, Bellatrix Lestrange should be able to tell Voldemort about 12 Grimmauld Place.
**However, it is possible that the Fidelius Charm does not work on elves, since it is shown multiple times in the books that elf magic works differently with wizard magic.
**It is also possible that Dobby merely Apparated right outside Shell Cottage for the Secret Keeper, Bill Weasley to lead them in.
===Chapter 27: The Final Hiding Place===
*Harry drips dittany through the singed hole in his jeans to the angry burn beneath, but he has just got changed, so he shouldn't be wearing his singed jeans anymore. Not much later in this chapter, Harry returns from an excursion into Voldemort's mind, and is "vaguely surprised" that he is "still wet to his skin", which he should not be since he had got changed into dry robes earlier. Harry may have been so affected by this excursion that he woke up in a cold sweat, but this is unlikely, since Harry has had a lot of experience seeing Voldemort's thoughts by this point, and because the statement implies that Harry's clothing is still soaked.
===Chapter 33: The Prince's Tale===
*When Harry is viewing Snape's memories, he witnesses a scene on Platform 9¾ between his mother and Aunt Petunia, in which Petunia tugs her hand out of Lily's grasp. Her hand is then back in Lily's, and she tugs it out again.
**Lily may have grabbed her hand again against her will.
*Dumbledore asks Snape to cast a Confundus Charm on Mundungus Fletcher, but since Voldemort took over the Ministry after the chase, Snape shouldn't have been able to enter Hogwarts and go to the Headmaster's Office. Unless Dumbledore showed him a way to enter unnoticed, had allowed him access, or something similar.
**It is also possible he used the Vanishing Cabinet in Borgin & Burkes to enter the Room of Requirement at night and thus sneak to the Headmaster's Office, or used the same passage through the Room of Requirement that the DA later used.
**Alternatively, he might have entered at day time and used a Disillusionment Charm in order to render himself almost invisible and spy on his former colleagues in order to find out what the password for the office is.
===Chapter 36: The Flaw in the Plan===
*Harry sees Charlie Weasley overtaking Horace Slughorn and in the next page Voldemort is seen duelling McGonagall, Slughorn, and Kingsley; however, Slughorn could have caught up again, possibly due to Charlie being distracted by something else.
==Notes and references==
Category:Media (Real World)