Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Continuity mistake: During the song "Its the American Way" Snake is robbing Hans Moleman during Chief Wiggum singing and Snake's hair is blue. His hair has always been a brown-red color. In the very next scene to confirm its a mistake you see him in the park saying "Yo Sherry Bobbins" and his hair is back to its brown-red color.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Revealing mistake: When Dr Hibbert is examining Marge's hairs (and I think another time in the episode), some holes are too low and you can see through her head.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Continuity mistake: When the family are watching Krusty Komedy Klassics, at the beginning of the show, they all have grey tables, with their dinner. But when Bart asks for milk, Marge gets up to get it and her table has disappeared. When she comes back the table has re-appeared.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Deliberate mistake: During the final musical number, just after Marge sings "I'm going bald from stress," the family sings "But we're happy just the way we are," but Homer's mouth doesn't move, because the producers forgot to record Dan Castellaneta's lines.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Continuity mistake: When Bart is lying on his bed whipping cupcakes at the wall, there are already 2 on the wall but after he whips the 3rd, there are still only 2 cupcakes on the wall.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Audio problem: When Shary Bobbins suggests to Lisa that they could have a tea party on the ceiling, Shary's lips don't match what she's saying.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.