Character mistake: Moe says that no women have been to his bar since 1979, yet in "Flaming Moe's" he hires a female waitress. Also, in the episodes "New Kid on the Block" and "Homer the Vigilante," Ruth Powers appears in the bar, and orders a beer in the former episode while Marge visited the bar in "Bart Gets Hit By a Car."
Revealing mistake: When everyone is cheering for Ned at the neighborhood watch meeting, Apu's hand is yellow.
Revealing mistake: When Homer is on the news talk-show talking to the cat burglar, he puts his hand on his chest and the opening of his shirt appears over his hand.
Revealing mistake: When Homer pushes the soda vending machine next to the candy vending machine, a large scratch appears near the upper right corner of the screen.
Suggested correction: This is in the questions as well. With the long amount of time the artists have to make an episode it's very hard that something like this would get by them. It's probably the device you watched it on.
Not true, watching a clip on Youtube and the episode on Disney+ the scratch is present. So it's not the device being used by the submitter.
Ssiscool
One Fish, Two Fish, Blowfish, Blue Fish - S2-E11
Revealing mistake: In the credits it shows Homer eating pork rinds. This is a reused scene from "Moaning Lisa."
Audio problem: During the party, when Princess Kashmir asks Homer to dance, her mouth doesn't move. (00:08:10)
Ned 'N' Edna's Blend - S23-E21
Continuity mistake: When Homer (playing Jesus) is on the cross and speaking to Snake, his stubble briefly flickers to yellow twice in the same shot.
Sideshow Bob's Last Gleaming - S7-E9
Factual error: Sideshow Bob couldn't hide out in the Duff blimp's helium pocket because there wouldn't be any oxygen.
Casual PersonBrother's Little Helper - S11-E2
Continuity mistake: When Homer and Marge are in the research lab, the scientist pulls off a white cloth which is covering the hamster tank and places a tube next to it, but in the next shot it's gone. (00:04:55)
iceolieThe Bart Wants What It Wants - S13-E11
Other mistake: Ned Flanders wins the $100 bill, but on the side it says $50.
kane raggettContinuity 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.
kane raggett
Continuity mistake: Before Krusty is arrested, he grabs a drink and there is no olive in it. When he sits down, an olive has appeared in the drink. (00:05:35)
Kill the Alligator and Run - S11-E19
Deliberate mistake: When Marge is sweet talking the sheriff, Bart unlocks all but Homer's foot chains, but when they're running for the gate, Marge, Bart, and Lisa's shackles can be seen.
dohContinuity mistake: When Homer says to Bob that he tells Marge everything, his hand is by his mouth, the shot cuts and it is at his side.
Ssiscool Margical History Tour - S15-E11
Factual error: On the castle where King Henry VIII is supposed to live, the flags at the top have the pattern of the English flag, being a + shaped cross on a coloured background, but it should be a red cross on a white background. Instead it's a white cross on a blue background. Those are the colours of the Scottish flag, but England and Scotland were separate countries at that point in history. And the cross on the Scottish flag is an X shape rather than a + shape anyway.
Team Homer - S7-E12
Continuity mistake: When Moe says Mr. Burns is going to have an accident, he's wearing his pin pals shirt. When Moe hits Mr. Burns, he wears a mask and different clothes. Moments later, when talking to his bowling team again, he's back in his pin pals shirt.
Continuity mistake: In the new opening sequence, Kearney and Dolph cut off Jebbidah's head. But in the pan of the city, the head is back.
Jason VoorheesSuggested correction: The pan of the city is before the head is cut off. After the head is cut off you don't see the statue again.
Ssiscool Continuity mistake: Towards the end, when the scientist is trying to give everybody diamonds, a shot cuts to just Marge and Lisa, but out of nowhere Maggie appears. (00:19:30)
Continuity mistake: When Homer is shot at the hippie farm, he ends up with a flower in his head, stem first. But he put the flower in the gun barrel stem first, as well. From a shot at that close a range and that velocity, there's no way the flower could have turned around in mid-air.
Cubs FanTree House of Horror X - S11-E4
Plot hole: In "Life's a Glitch", Lisa finds out that she has a seat on the spacecraft going to Mars as the proofreader. How, though, was she not informed of this before going to the rocket? The family only finds out about the rocket after finding Krusty's letter/invitation and the fact that she was on the list there would be no reason why she wouldn't have been informed of this. It was still New Year's Day so if it had been by mail then it would have to arrive before the New Year so as to make the plan work, being as it was a public holiday and no mail would be delivered. Therefore it would have to be delivered personally or someone would need to contact her. There were also many well known celebrities and figures ready to board the rocket. I can't imagine they were all home in time to gather their mail and were all somehow contacted, yet Lisa was simply walking around town and at church and they couldn't find her? There was also no evidence to suggest anything would have stopped her from either receiving the invitation in time or being informed of the mission.
Lummie 
