Continuity mistake: Before Homer sees his vision of Caesar Romero the day sign next to him says 9. After the Duff executives see him talking to nobody they decide to take him away and when they get down there the sign now says 12 with the president of Duff confirming it in his speech. Doubtful it took them 3 days to get down to him and not much reason for Homer to take 3 days off the sign seeing as he was almost passing out from the lack of food.
Continuity mistake: Just before Marge tries to sell Skinner the tie rack, she is writing on something. She then puts her hands down by her waist, and then brings one up to turn it on and both up to pull the motor out. The point is that the pencil and the item she had in her hands have simply vanished, and we never saw her put them down either.
Tree House of Horror VI - S7-E6
Continuity mistake: When Professor Frink is explaining where Homer is, in "Homer3", Ned Flanders is leaning behind the couch between Bart and Marge, and Chief Wiggum is standing up. When Homer complains, Ned is between Marge and Chief Wiggum, who is now sitting down on the couch.
Continuity mistake: When Santa's Little Helper is taken away by the Repo Men, the van's back bumper is first seen to have no number plate. When the van drives off, there is a number plate.
Tree House of Horror VI - S7-E6
Continuity mistake: For most of "Homer3", Marge's shoes are red. When Frink explains that Homer is 3rd Dimension, Chief Wiggum says, "Slow down, egghead". During this shot, Marge's shoes are green. When Homer complains, Marge's shoes are back to red. (00:18:05)
Continuity mistake: When Lisa is interviewing people for her newspaper articles, the order is Nelson, Ralph and then the two purple twins, Sherry and Terrie. But after Ralph has been seen, it is not the twins but a totally different person, Lewis. (00:07:30)
Continuity mistake: When Lisa is first delivering her newspaper, Red Dress Press, she unties a pile and the strings are untied. Then the shot changes and the pile has been done up instantly. (00:05:55)
Lisa's Date with Density - S8-E7
Continuity mistake: When Jimbo and Co are 'coleslawing' Skinners house, he wakes up when coleslaw hits his window. When the shot moves to outside, there isn't any coleslaw on any of the windows.
Radio Bart - S3-E13
Continuity mistake: When Marge puts Maggie to bed, her pacifier changes from red to light brown between shots. (00:08:10)
Days of Wine and D'Oh'ses - S11-E18
Continuity mistake: The police car door doesn't appear on Barney's arm until they watch the video.
Continuity mistake: As Martin reveals his Honor Rollor at the time trials, we can see Bart on the right side of the screen. He suddenly appears beside his car in the next shot. (00:13:00)
Lisa's Pony - S3-E8
Continuity mistake: At the end, the melted cheese and work outfit disappears from Apu's hands. (00:21:20)
Lisa's Pony - S3-E8
Continuity mistake: In the kitchen, there is a clock on the wall that changes time from 07:10 to 09:10. (00:12:10)
Lisa's Pony - S3-E8
Continuity mistake: Before Lisa licks the salt lick, there is another horse in the stable which disappears. (00:14:30)
Tree House of Horror II: A Simpsons Halloween - S3-E7
Continuity mistake: Maggie gets her new pacifier and puts it in her mouth. She has her normal pacifier for the rest of this part. (00:04:05)
Tree House of Horror II: A Simpsons Halloween - S3-E7
Continuity mistake: At the beginning of part 1, during the first two shots, Lisa's in a diferent position, and Marge has vanished. (00:02:25)
Continuity mistake: When Bart crashes at the door of the Legitimate Businessman's Social Club, his head is facing the door. You can only see this for several frames. In the next shot, his head is facing the sky. (00:05:25)
Continuity mistake: In the scene where the bullies are talking to Bart and Ralph on the street corner, they move positions between shots. They change from a straight line to being in an arc shape, to being in a group.
Continuity mistake: In the scene in Ralph's bedroom the nightlight changes positions between shots. First it's far away from the doorway, then near to it, then right next to it.
Continuity mistake: When Marge is putting Lisa and Bart's clothes on, she puts Lisa's dress on Bart and Bart's shorts and t-shirt on Lisa, but 2 seconds later, when they are entering the kitchen, they are wearing their normal clothes.