Little Girl in the Big Ten - S13-E20
Continuity mistake: After Lisa's dream she lines up and the girl on the bars is the same girl the teacher told to go out.
The Last Of The Red Hat Mamas - S17-E7
Character mistake: When Homer finds Marge's folder, it reads "Heist Plan: Burns Manson" instead of "Mansion" as it should be.
Continuity mistake: When Homer buys Ned's living room for $75, Bart is wearing a pink "Ned loves Maude" T-Shirt but by the end of the scene where Bart says "Hands off my china hutch." his shirt is the standard orange shirt. (00:14:40)
Continuity mistake: In the park, Marge's necklace changes from white to red. (00:15:40)
Continuity mistake: During Sadgasm's first appearance, a girl with a green skirt, a red sleeveless shirt and grey hair moves from place to place during the "concert."
Itchy and Scratchy: The Movie - S4-E6
Continuity mistake: In the scene where Marge is talking to Bart's teacher, Marge is "punished" by writing lines on the blackboard. In the first shot of her doing so she has written the line 9 times, but in the next shot there are 11 lines. (00:05:10)
Treehouse of Horror XIII - S14-E1
Continuity mistake: The beers Homer puts under the hammock vanish when the hammock breaks, and Homer falls to the floor. (00:01:15)
Continuity mistake: After Homer falls asleep at the wheel the truck starts to turn the corner. As its going around the bend you can see a white line on the road. The following shot the line has disappeared.
Tree House of Horror XII - S13-E1
Continuity mistake: In the opening sequence, when the coffins shoot out of the grave, one of them changes colour between shots, when it hits the pillar. (00:00:25)
New Kids on the Blecch - S12-E14
Continuity mistake: When Bart and the group are singing at school, when we see L.T.Smash, his arms are down then instantly in the next shot, they're on his sides. (00:08:10)
Sleeping with the Enemy - S16-E3
Continuity mistake: When looking around the course at the beginning we see there is a spinning toy, which you find in some parks, yet when Willy comes along, it has disappeared in the distance. (00:00:40)
Tree House of Horror V - S6-E6
Other mistake: At the speed that Homer was chasing the family outside the lodge at the end of "The Shinning", he would have caught them up with ease.
Tree House of Horror VII - S8-E1
Continuity mistake: In "The Thing And I", Bart discovers he has a scar where he was separated from Hugo. During the attic scene, it disappears. (00:04:40 - 00:06:10)
Continuity mistake: In this episode and maybe in other one, the door to the basement is at the entrance of the house, but that's a closet in other episode.
The Great Louse Detective - S14-E6
Continuity mistake: When Bob pins Bart onto the wall in the final scene, his pajama top is stretched up so you can see his stomach. It then zooms in slightly when he looks at his watch and his stomach is covered.
Tree House of Horror IX - S10-E4
Audio problem: At the end when Bart says 'Don't forget Ken Star' his mouth doesn't move.
Audio problem: When Marge says she wants the padding that goes under rugs her lip movements don't match what she's saying. (00:13:25)
There's No Disgrace Like Home - S1-E4
Audio problem: When Marge gets drunk at the picnic, she falls on Homer while saying "Homie, did you try the punch?", her lips don't move. (00:06:20)
Homer vs. Lisa and the 8th Commandment - S2-E13
Revealing mistake: When Homer is imagining being locked in the jail cell and he turns around to find he is in his own home, he turns to look at his family. There is a close up shot of his terrified face, and the people in the background watching the game (I think it might be Lenny and Carl) have no eyes. The rest of their face is fine, but their eyes are missing.
Tree House of Horror X - S11-E4
Continuity mistake: In the 'I know what you did-diddly-did' story, the Simpsons car keeps changing from dark purple to the normal pink colour.