Audio problem: When Marge says "Save our families" at the beginning of her petition, her mouth doesn't move.
Continuity mistake: In the bathroom, Lisa can't stand the Roofi CD being played so she pulls the plug out of the plug socket to stop the radio playing. In the next shot, the plug has disappeared from the radio.
Other mistake: In the DVD booklet, two errors are made for this episode. The booklet says Homer accuses Bart of ruining Thanksgiving and Bart was jealous of Lisa's centre piece. These are both incorrect: First, it wasn't Homer who accused Bart of ruining Thanksgiving, it was Marge who accused Bart of ruining Thanksgiving and second, at no point throughout the episode was Bart ever jealous of Lisa's centre piece.
Audio problem: In "Clown Without Pity" when Homer is singing in the bath, his mouth doesn't match what he is singing.
Continuity mistake: When Homer and Bart are watching a clip of Sideshow Mel on wowee sauce and Bart then says "I'd give anything to go to that show", he has nothing in his hand. The shot cuts to Homer and he then says "I'd sell my first born son" and then the shot cuts back to Bart. When the shot cuts back to Bart, a Buzz cola can has appeared in his hand out of nowhere.