Diane is Betty
Betty is not a real person. Diane only created her vulnerable, kind character in her imagination because she felt bad about what she did. Diane wished she was Betty.
Diane took cocaine out of stress
In the beginning of the film, we see Diane’s apartment and we hear cocaine snorting. Diane started taking cocaine when she felt bad about killing Camilla.
Diane imagined the whole story
All the events we see in the beginning of the movie weren’t true; the scenes seemed exaggerated because they only happened in Diane’s imagination.
Diane was jealous
Diane planned on killing Camilla after she found out that Camilla was in love with the director that she starred in his movie.
The silenco show opened the door to reality
The idea of the silenco show was to show the audience that the first part of the movie wasn’t real. That’s why the host kept repeating ‘No Hay Banda’ which means there was no band or orchestra and that it was not a real theater show; everything we heard was a recorded tape.
The key unlocked the mystery
The blue key that opened the box was the key to the mystery of the whole film where it’s no longer Diane’s fantasy; it was the real story. (See The Devil’s Candy (2017) Movie Explained)
The dirty man represented evil
Diane imagined the dirty man because that’s how she felt about herself after killing Camilla. The dirty man resembled Diane’s evil side.
Diane’s imagination was derived from reality
All the people she saw in her fantasy were people she already met in reality, like the directer’s mother, Coco, who was the landlord of Diana’s aunt building in Diane’s fantasy. (See The Witch (2015) Movie Explained)
Diane killed herself
Diane had the idea of killing herself before she actually did it because she wanted to annihilate her real character and keep the good, fake version of herself, Betty. Later in ‘the reality’ part, she hears that some officers came and asked if she was there then she panicked and kill herself.
The hit man killed Camilla
The blue key that the hit man left on Diane’s tea table proves that killed Camilla. The part, however, where he was asking around about a missing girl was only in Diane’s imagination because she wished that Camilla had escaped and that the murder never happened.
Camilla was Diane’s ex-lover
Diane was obsessed with Camilla, but when she knew that Camilla was not interested in her anymore she got really angry and planned that whole thing.
Mulholland Drive Movie (2001) Explained
Mulholland Drive: A complete explanation of David Lynch’s Movie | Understanding Mulholland Drive Film