Audio problem: During the "Sparke Motion" dance scene, the dance instructor is mouthing the wrong words to the song the girls are dancing to. "West End Girls" by the Pet Shop Boys was originally going to be the dance number, and that is actually the song playing for the recording of the scene. Richard Kelly couldn't get permission to use it, and "Notorious" by Duran Duran was substituted. The teacher is plainly mouthing words from the wrong song.
Audio problem: In the first dinner scene, look closely at the way Eddie Darko's mouth moves as he laughs after the "What's a f***ass?" question from Samantha. He takes a bite of his pizza, and his mouth movements do not match the sound of his laughter.