Rookies " Rookies " is the fifth episode of of " " television series . It is the fifth episode of the series overall . It first aired on Cartoon Network on October 24 , 2008 . It was later shown on TNT , premiering on February 25 , 2009 . Official description . " Alone on a distant outpost , Clone Commander Cody and Clone Captain Rex must inspire the rookie clones to believe in themselves to stave off a Commando droid invasion . " Plot summary . On the remote Rishi moon , a small unit of rookie clones stationed there , including Hevy , Echo , Fives , Droidbait , and Cutup are restless and deprived of battle . Echo reads reg manuals while Hevy daydreams of being on the front lines when Sergeant O ' Niner reminds them that their listening post is vital in keeping an eye on Separatist activities and making sure they do not try to slip past and launch a surprise attack on Kamino , the center of clone production and training . The Sergeant orders his men to prepare for an inspection by Captain Rex and Commander Cody , who are en route . Soon after , the station detects an incoming meteor shower and prompts it to raise its shields . But the meteors " aren ' t " all meteors — two of them are boarding ships carrying several droid commandos . With brutal efficiency , the droids infiltrate the base and waste no time in executing Sergeant O ' Niner along with three rookie clone troopers , forcing the remaining four clones to flee the base through the exhaust vent . The commando droids report their success to General Grievous . Pleased , Grievous contacts Asajj Ventress on Kamino , where she is making secret preparations for a Separatist invasion . Meanwhile , Cody and Rex contact the Rishi station as they enter the system . The commando droid leader adjusts his vocabulator to mimic a clone ' s voice , puts on a helmet , and tries to trick the two officers into canceling their inspection . Rex and Cody are suspicious when the " clone " says " roger , roger " , and continue toward the base . Hevy , Echo , Fives , and Cutup emerge from a maintenance tunnel into a deep crater below the outpost and plan their next move . Suddenly a massive Rishi eel silently emerges from one of the many caves in the crater , snatches Cutup in its jaws , and disappears back into its hole taking the other rookies by surprise . Just then Cody and Rex ' s shuttle flies in for a landing high above . Hevy , Fives , and Echo are unable to make contact by radio , so they decide to use a warning flare . Up on the platform the clone officers are met by a peculiar " clone " who gestures awkwardly and talks like a droid . The " clone " tries to convince them that the base is in perfect condition right when Rex and Cody notice the flare sent by the real clones . With the appearance of the warning flare , Rex immediately shoots the impersonator , revealing it to be a droid commando in disguise . Suddenly more droids begin to attack them and destroy their ship with thermal detonators . Under the cover of the explosion , Rex and Cody escape into the crater where they meet up with the rookie clones . Suddenly , the eel comes back right when Rex shoots it in the eye . They explain to the rookies that they need to take the base with their new support . Rex and Cody are determined to retake the base , and Hevy , Fives , and Echo are up for the task . Rex poses as a droid in armor , using a severed droid head to convince the droid guards to open the door . The clones charge into the base , killing the droid commando commander and quickly regaining control . Unfortunately , the Separatist navy led by Grievous has arrived , and when he can ' t make contact with the commandos , Grievous sends down reinforcements . Not wanting the base to fall back into enemy hands , the clones resolve to blow it up with liquid tibanna , which would disrupt the all - clear signal , thereby alerting the Republic . As the other clones escape through the tunnels , Hevy tries to arm the explosives but the remote doesn ' t work , so he decides to activate it manually . In a heroic last stand , Hevy is felled , but not disabled , and he activates the explosives . The base , along with Hevy , is destroyed . Alerted , the Republic fleet jumps into the system and Grievous is forced to retreat . When they return to the " Resolute " , Echo and Fives are granted medals and Rex inducts them in the 501st Legion . The rookies feel they don ' t deserve the honor , but Rex says they ' ve earned it . " " You showed me something today . You ' re exactly the kind of men I need in the 501st . " " - Rex to Echo and Fives during the latters ' induction to the 501st legion . Behind the scenes . In the original showings of this episode on Cartoon Network , the word " Hell " was used as an expletive twice . During the replay on November 7 , 2008 , before Downfall of a Droid premiered , the word was censored due to complaints from parents . When broadcast in Canada , neither CTV nor the Space network censored it , however the series is rated 14A in Canada , roughly equivalent to PG - 13 . During its showings on TNT , the word was not censored . However , in the iTunes version , it was censored only once . When the droid posing as Sergeant O ' Niner tries to convince Cody that no inspection is necessary , it mimics Han Solo ' s lines " " We ' re all fine here now , thank you " " from " A New Hope . " On the screen of the detonator used by Hevy to destroy the base , the words “ ATTE RUL3Z SOME TEXT ” can be found written in aurebesh . When Fives and Echo are awarded their medals the camera is behind them and Echo is just holding his hand out with out a helmet . And when the camera is front of the clone trooper Echo is holding his helmet . Almost two years after the original airing of " Rookies " , a prequel episode and a sequel episode aired on Cartoon Network as the premiere of the on September 17 , 2010 . Continuity . In the scene when Echo and Fives are receiving their badges , Echo is seen without his binocs , but on the second scene he is seen with the binocs on his helmet .