It's a Mad, Mad, Mad, Mad Marge - S11-E21
Continuity mistake: When Homer is changing the oil in Marge's car, he is in his own driveway, but in the next, he is perpendicular to Flanders' house and then in Flanders' driveway.
Suggested correction: He is in his own driveway the whole time. There's never a shot of him in a different position and certainly never in Flanders' house. You ever see the brick wall from the Simpsons' house in the last shot.
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.
Tree House of Horror XI - S12-E1
Continuity mistake: In Reaper madness, there's a scene which Homer wakes up being the grim reaper, he puts the robe on at which point he is wearing a singlet. In the next scene where God turns Homer back to his regular self he is wearing his white shirt.
Tree House of Horror XI - S12-E1
Continuity mistake: In the "Scary Tales can Come True" segment, Bart's plague rat bite disappears for the rest of the segment.
Continuity mistake: When Krusty is telling his daughter that he lost her violin, keep an eye on the door of the appartment. A grey bar appears and disappears on the door underneath the "eyeglass" between shots.
Continuity mistake: After Amy Tan shames Lisa, there is a shot of Lisa wearing a red necklace, her necklace becomes her usual white one, seconds later.
Continuity mistake: Bart's magazine appears in the second shot of him and Lisa talking, it's not in the first.
Revealing mistake: When Lisa wraps herself in Marge's arms right before she falls asleep, the inside of her mouth turns yellow.
Continuity mistake: When Homer, Lenny and Carl are in the cafeteria, and Homer is drinking beer, his chair changes from being blue, to red, then back to blue again, between different shots. (00:06:45 - 00:07:15)
Plot hole: In the last part of the episode, when Mr Burns is trying to convince Homer on his float to play a big prank, the timing is totally wrong. Firstly, Lisa sees the writing 'Happy Pranksgiving' on the side of Mr Burns' float way before it reaches her, and it takes Mr Burns ages to change into the Father Christmas outfit.
Deliberate mistake: The mouth on the panda costume is in a constant smile and at no point does Homer change it, even when he is in pain. However, when he is being pulled back under the curtain the mouth is open and the mask has a frightened expression. I suppose this was done on purpose, but it's still a continuity error of sorts.
Continuity mistake: When the Simpsons are at the restaurant at the start, Bart has no medal on his jacket. But when Lisa remarks a few seconds later that Homer gave Bart a medal, one has appeared on his jacket.
The Great Money Caper - S12-E7
Continuity mistake: When they are driving home Marge starts to moan at the children to quiet down. In this shot she has no lipstick. In the next shot from outside the car she has lipstick on and has it for the rest of the scene.
Skinner's Sense of Snow - S12-E8
Continuity mistake: When Skinner dismisses the kids from school, we learn the snow level is near the top of the windows and to the top of the doors. But in the next scene, we see a shot of Springfield and the Simpson home, where the snow level is to the bottom of the door. (00:08:02)
Skinner's Sense of Snow - S12-E8
Continuity mistake: When the hamster Nibbles has rolled back to Skinner, it takes the lid of the ball off, and the lid lands on the ground. When the hamster is rolling away from Skinner it doesn't put the lid back on, it just leaves it on the ground, but in the next shot the lid is suddenly gone.
Skinner's Sense of Snow - S12-E8
Factual error: Superintendents are the ones who decide whether or not schools should be closed for snow days, not school principals.
Skinner's Sense of Snow - S12-E8
Continuity mistake: When the children are sleeping in the canteen at school, Bart is resting his head on a red sweater. In the close up of him and Lisa, the sweater has now turned dark green. It's not because of the dark that we see it like that because there is a bit of light at the beginning of the next shot and we see the jumper to be dark green.
Skinner's Sense of Snow - S12-E8
Audio problem: When Principal Skinner is watching the kids throw the books in the fire, someone goes to throw Huckleberry Finn into the fire. He says "Not Huck Finn. I spent hours crossing out the sass-back." While he says this, his lips don't sync with the words.
Skinner's Sense of Snow - S12-E8
Continuity mistake: When the Hamster rolls through the glass of Flanders car it breaks it near the bottom middle of The Front windshield. Later on when Flanders and Homer are taking the kids home you can see the break in the glass has now moved to about halfway up The Front windshield. On of the following shots it moves back to its original position and then moves back to being around the middle of the windshield.
Continuity mistake: When Homer sits down in the movie theater, all the rows are completely full, including the row behind him. When he turns around to talk to Selma, the seats directly behind him are empty. Then, when Homer turns back to the screen, the Sea Captain and Dr. Hibbert appear sitting directly behind him.
