During Neil's "concert" for Violet, she accidentally burns a cardboard cutout's eye. Later when Neil is crying over their breakup while ringing up a customer, it shows the cutout burn-free.
When Neil and Violet go to the cat lady's house to watch the game, the cats constantly keep changing spots between shots.
Violet says she doesn't have a driver's license, but she still manages to drive a car to Neil's house. However, she may have told Neil that she didn't have a driver's license just to see how he'd react, just like almost everything else she did to him.
When Violet interrupts Neil's bath and he is supposed to be naked, he is wearing some kind of cloth to cover his masculine parts.
The copyright notice at the end of the credits ("This Motion Picture Is Protected...[etc.]" has an error. Further on, it states, "Or Copying Of This Film Of Any Part ...[etc.]," but it should read, "Or Copying Of This Film OR Any Part ...[etc.],"
When the envelope goes missing that has Violet's 50 bucks, Neil never suspects her of taking it, even though he already thought she was weird.