Mulholland Dr. is about lots of things, including...

Rating: 10/10 (14 December 2002)

I think that a major theme of the film is about discovering things and then having to deal with these discoveries. Perhaps it's to do with dreaming, I don't know, but Betty initially comes across as an innocent, who stumbles upon mysterious things. Her eyes widen in wonder when she arrives in LA, and she can't believe her Aunt Ruth's place; but then... who's that in the shower? A stranger? Why is she here?
What about Diane Selwyn and the body in the house? The scene in which Betty and Rita find the corpse is filmed so slowly, so carefully: Lynch must really have enjoyed shooting this scene.
The scene in the theatre when it is revealed that the singer is miming: This has a shattering impact on the two women.
It's not just Betty and Rita who discover things: Angelo Badalamenti's character is sweaty with anticipation as he takes his friend behind the diner to show him where he saw the figure in his dream.

And then there's the scene near the beginning, when the car is weaving through Mulholland Dr. A similar scene recurs throughout the film.
Of course there are explanations for many of these things, but I think that the reason why they are 'there' in the film is to create a sense of the wonder and the terror of discovery.