Audio problem: When Miguel and Steele are collecting some more of the zombies, Steele says 'Nice hat, asshole,' and laughs. Watch carefully at the end bit: they dubbed a laugh into the movie, but it's painfully obvious that his mouth doesn't move as he does it.
Audio problem: When Jesse and Ron are doing press-ups on the sports field, Ron says "So what about you and that rich babe you've been cruising to school with every day?" You can see that Ron starts to move his mouth a few seconds after the words are spoken, and his mouth doesn't move correctly to the words being spoken either. (00:10:30)
Audio problem: When Junior is riding his motorbike around, screaming "they hurt me, ma," in many wideshots we hear him yell but his mouth is closed. (00:55:20)
Audio problem: Right before Charley gets thrown into the closet doors, Jerry has him by the throat threatening to kill his mother if she wakes up. In the shots of Charley trying to free himself of the grip, Jerry's lips are moving but no sound can be heard. (00:28:15)