Continuity mistake: In "Terror at 5 1/2 Feet", when Milhouse decides that he is going to sit next to Uter, Uter all of sudden moves to the other side of the seat between shots.
Continuity mistake: At the end just before the Simpsons say "Happy Halloween everybody" they are about to bite Lisa (and make her a vampire). Maggie has no dummy (or in America, pacifier) in her mouth, but it suddenly appears when she closes her mouth.
Continuity mistake: When Otto hits Hans Moleman's car, it has a number plate on it, which disappears when he crashes.
Continuity mistake: When Chief Wiggum and Homer think that the convertible Ruth and Marge are in is a ghost car, they want to hold each other. In this shot, you can see 1 small star out of the backseat of the police car. But in the next shot, from the perspective of the backseat, there is a canyon top where the star would be.