Mulholland Drive's secrets unveiled (SPOILERS)

Rating: 10/10 (27 October 2001)

Unlike most films, Mulholland Drive needs to be interpreted like a novel rather than just watched. To be sure, there are events that take place; but the significance and context of those events are what makes this film mean different things to different people. I will try to explain the three most popular interpretations.
1. The easiest and most common interpretation is that the first part of the film is a dream, and the last half hour is reality. Before the opening credits, we see a montage of Betty with the elderly couple, then the jitterbug sequence, then some red bed sheets and pillow. The bed sheets and pillow signify that what we are about to see is a dream. In the dream, Rita gets amnesia after a car crash and she is helped by her friend Betty. Betty is smart, pretty, confident, and a talented actress. In trying to find out Rita's true identity, they fall in love. But then the dream turns to a nightmare as they go to a club called Silencio, where Betty comes into possession of a blue box which Rita has the key that opens it. When the dream is over, we find out the dreamer is Diane, who played the role of Betty in the dream. Her ex-lover Camilla was Rita in the dream. In this reality, Diane is not successful or confident, but Camilla is the stunning and successful one. Camilla has ended their relationship, so out of jealousy and envy, Diane pays a hit-man to kill her. After the murder, she is overcome with guilt and kills herself.
2. In this interpretation, both the women are dead but do not realize it. There have been a couple of movies in the last few years to use this sort of plot device. Diane's dream of the first part of the movie is a dream within a dream. You will notice that all the plot threads start while Rita is sleeping. It is because it is her dream also. The elderly couple with Betty before the opening credits are her companions on her plane trip. They represent spirits of the netherworld. At the end of the movie they take her back. At Silencio, they see a singer die on stage, but they can still hear her voice. This is symbolic of them realizing they are dead but still conscience. The blue box represents the soul. Rita has the key, but she needs Betty in order to get the blue box. Once she opens the blue box, she is transported to where people go when they die. After that, Diane wakes up and thinks she has been dreaming. Virtually all of the last half hour of the movie is either flashback or delusion. Betty's blue box is owned by the evil person behind the coffee shop, placed in a wrinkled paper bag like it was garbage. The guardians of the netherworld chase after Betty. Betty escapes by killing herself. There is a montage at the end where Betty and Rita are together. This could mean that Camilla has forgiven her and they are together in the afterlife.
3. The two women are the same person or one is an alter-ego of the other. There have been a couple of films in the past year to use this plot device also. One of the important parts in this interpretation is that Diane is told she will find a blue key when the murder is done. But in the dream it is Rita who has the key and the money. In the first part of the movie, Rita is the dreamer and Betty is the alter-ego. After she wakes up, Diane is real and Camilla is the alter-ego. The alter-ego is always the successful and talented one. The montage at the end where the two women are together signifies that the duel personalities have consolidated.
I realize I did not go into a lot of detail to argue for any of these interpretations, but if you watch the film closely, you will find things to support each interpretation. I believe all three are equally valid but I do not know which one David Lynch intended. Not that it matters. If you have seen Mulholland Drive, but did not really understand it, then I encourage you to see it again with these things in mind and pay close attention to the details.