Sweets and Sour Marge - S13-E8
Continuity mistake: When Homer dumps the sugar into the ocean, the hand pressing the "dump cargo" button has a yellow shirt cuff. Homer is wearing a white short-sleeved shirt.
Sweets and Sour Marge - S13-E8
Continuity mistake: At court, when Garth Motherloving tells Judge Snyder "I'll kill you while you sleep", the blue haired lawyer's suit is green. His suit is grey in all other shots of him.
Continuity mistake: In the cinema, it is clear that the people attending the movie keep on changing. For example, For a few shots, you can see that Krabappel and Skinner are sitting in The Front row, but the next time you see those seats, they have been replaced by Lenny and Carl and Krabappel and Skinner aren't in sight.
Continuity mistake: When Marge and Homer are at the Springfield formal ball at the Country Club, about half way through the ball, there is a woman with her back to the camera as she is talking to Marge and Homer. Homer is on Marge's left side. In the next shot when Marge's back is to the camera and you can see Marge still talking to the woman, Homer is no longer on Marge's left side, he is gone.
Continuity mistake: When Duffman says "Duffman can never die, only the actors who play him", his red briefs are missing.
Half-Decent Proposal - S13-E10
Audio problem: The lady singing at the prom doesn't move her lips when she sings, her mouth just stays open.
The Bart Wants What It Wants - S13-E11
Continuity mistake: When Bart is in the ice cream parlor breaking up with Greta, the waiter tells him "We get that a lot around here" and point over to Chief Wiggum and Lou sitting behind and to the left of Bart. Bart turns his head all the way to the side to see them. The focus then goes to Chief Wiggum and Lou, but when their part is done and the "camera" goes back to Bart and Greta, the policemen are sitting behind and to the right of Greta, so that Bart would not have had to turn his head to see them.
The Bart Wants What It Wants - S13-E11
Other mistake: Ned Flanders wins the $100 bill, but on the side it says $50.
The Lastest Gun in the West - S13-E12
Continuity mistake: At the start of the episode, the dog eats Bart's clothes through the letterbox, but a minute later, when the dog next comes to the house and Homer opens the door, there is no letterbox.
The Old Man and the Key - S13-E13
Continuity mistake: After Homer's father, Abraham, comes home after a night out with Zelda, Homer snatches his keys away from them. He leaves his hand out and begins outstretching fingers one by one to represent all the people he called in worry, and it's clear that the keys have disappeared.
Tales from the Public Domain - S13-E14
Continuity mistake: In the Troy scene, the letterbox outside the wall suddenly appears when the shot looks down to it. It wasn't there before and it isn't afterwards.
Weekend at Burnsie's - S13-E16
Audio problem: There is an elaborate bass line right at the end of Phish's song; however, the bassist's fingers don't even move. There's no way he could play that line without moving his hand. (00:13:50)
Gump Roast - S13-E17
Continuity mistake: When Kang and Kudos are electrifying Krusty; when they stop his clothes are fine for one split second, then the clothes are destroyed.
Gump Roast - S13-E17
Deliberate mistake: Where do the "professional roasters" get those home movies of Homer's stupidity? No one could possibly have filmed his skiing mishap or the Funzo incident. Also, how does Maggie keep a mental record of celebrities that she didn't meet in person?
Continuity mistake: At the end in the hospital, Maggie's bow is red for a second, then it changes to blue.
Continuity mistake: All through out the episode, Bart draws his pictures with only one pencil, but they all end up in color when he's done.
Factual error: When the creator of Danger Dog draws a picture of Skinner on a notepad and puts it on the projector, it is perfectly visible. It shouldn't have been, seeing as the pad was so thick.
Continuity mistake: When Homer falls into the pool with green paint, most (but not all) of him is covered with paint. In the next close up shot, he's completely covered in paint.
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.
Little Girl in the Big Ten - S13-E20
Revealing mistake: When Bart says "I don't feel so good" after being bitten by a mosquito, his lower body under the table is not visible.