Continuity mistake: Nelson makes a hole in the Honor Roller during the finals. This hole disappears and reappears between shots. (00:20:00)
Continuity mistake: When Dave gives Homer the Bill Cosby book, the cover is light blue. When he reads the book in the garage, it is green. (00:09:40 - 00:11:30)
Continuity mistake: When Chief Wiggum finally climbs the stairs his gun is visible to be a black, old style revolver with a curved handle. In the next shot where he draws his gun, it is a grey, new style handgun.
Continuity mistake: When Otto is playing the guitar with bart in the middle of the night, there are close-ups of Otto whenever he is singing. You can see that the wall behind him is plain. However, when there is a wide shot of otto and bart, the wall behind otto has two tables leaned against them. (00:15:50)
Continuity mistake: When Bart uncovers the photo of the Simpsons behind the books in Lisa's locker, the books change between shots.
Homer vs. Lisa and the 8th Commandment - S2-E13
Continuity mistake: When the door is answered to Mr Burns and Mr Smithers, Barney is seen answering, who has orange sleeves. However when the door is opened, you can just make out a white sleeve, which could be none other than Homer's.
Continuity mistake: When Homer is showing his BBQ invites to the kids Bart comes and stands next to Lisa and points to the extra 'B'. In the next shot, he's back over near Homer.
Continuity mistake: When Homer first lifts the corpse up, it is wearing glasses. But when it cuts to the shot of the corpses' face, the glasses have gone.
It's a Mad, Mad, Mad, Mad Marge - S11-E21
Continuity mistake: When Marge is sitting with Patty and Selma talking about Becky taking over her family, Selma has some sort of drink. As the shots change, she goes from having half a glass, to a full glass, to having no drink at all.
I, (Annoyed Grunt)-bot - S15-E9
Continuity mistake: The cats' graves change position. When Snowball II is buried, they're away from the the tree and near the fence. When Snowball III is buried, the graves are away from the fence and Snowball is among the roots of the tree. (00:04:10 - 00:09:25)
'Tis the Fifteenth Season - S15-E7
Continuity mistake: Homer looks out of his bedroom window at the skating rink he has built in his back garden. Homer and Marge's bedroom is usually at The Front of the house. (00:13:50)
Continuity mistake: When Bart and Skinner are checking lockers, you can see in a wide shot that Bart needs to check seven lockers before he gets to Lisa's locker. However, Bart checks eight lockers and then opens Lisa's locker. (00:19:35)
Continuity mistake: In the cafeteria scene where Milhouse shoots a spitball at Kearney, in the shot when Milhouse says, "We have order, but at what price," Milhouse, Lewis and the bullies all change positions at their tables. You may have to watch this part several times to understand it. (00:16:45)
Burns' Heir - S5-E18
Continuity mistake: Burns' top hat disappears from the bath at the start.
Continuity mistake: During the wedding, when seen from behind Reverend Lovejoy, there is no podium in front of him (although his hands are poised in mid-air as though one should be there). In the reverse shot, the podium has magically reappeared. (00:20:00)
Continuity mistake: When the salt spills on Milhouse's food, the table full of kids in the background has disappeared. (00:10:45)
Homer's Barbershop Quartet - S5-E1
Continuity mistake: In the deleted scene where the Be Sharps unveil 'Donut Records', Barney's hair flashes red a couple of times in the close-up of the band.
Tree House of Horror X - S11-E4
Continuity mistake: In "I Know What You Diddly-Iddly Did", just after Ned has been run over, he turns from a werewolf into his normal self. If you look carefully, his left ear turns brown for a second before turning yellow again.
Homer's Triple Bypass - S4-E11
Continuity mistake: In this episode, Homer closes the curtain on Ned when he is praying. And the curtain is blue. However, a few scenes afterwards, when Homer is talking to Krusty, the curtain is green/beige. (00:14:10)
Continuity mistake: When Homer and Marge come home from the dinner, Marge is wearing a fancy dress. But when Bart falls out of the house right after Homer walks in, she has her typical green dress on. (00:06:15)