Tree House of Horror XII - S13-E1
Continuity mistake: At the end of 'Hex and the City,' there is a shot of the wedding cake, then it pans across the people at the wedding, and you can see Homer with his white shirt on. But then when it goes to a closeup, he suddenly has a blue suit and tie on. (00:06:45 - 00:07:20)
Continuity mistake: At the end of the episode, Homer puts a skull in a box on the coffee table. When Moe arrives to explain his theory, first the box disappears from the coffee table, then the entire table vanishes.
Sweets and Sour Marge - S13-E8
Continuity mistake: When Homer falls off the human pyramid, he grabs onto someones rear end to stop himself from falling. In the next shot, he is suddenly holding a foot.
Continuity mistake: When the family are returning from the picnic, they pull into the drive and Homer has a seatbelt on in some shots, and in others he isn't wearing it. You can't even see it attached to the side of the car sometimes.
Continuity mistake: When Homer first finds the corpse, there is no belt on the trousers it is wearing. But in the shot where Homer starts to scream, there is a belt on the trousers.
Tree House of Horror XII - S13-E1
Continuity mistake: At the show the school puts on in "Wiz Kids", when the Montymort Dragon is first seen in the cage, the cage has 6 bars at The Front. When Lisa says "Release The Dragon", the cage has 4 bars. When the cage door is being raised, it has 6 bars again. (00:18:45)
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.
Continuity mistake: When Marge throws the Burly paper in the water, they start growing and sucking up the water. But the things inside that rolls don't grow.
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.
Continuity mistake: When Homer opens up his bar there are 4 cars parked outside, but later when Moe opens the garage door there are no cars, but no one has left.
Tree House of Horror XII - S13-E1
Continuity mistake: In the classroom scene in the school Nelson is beating on Milhouse and leaves his head black, but when they go to get graded Milhouse is in front of Lisa (not Nelson) and his head is normal.
Tree House of Horror XII - S13-E1
Continuity mistake: In 'House of Whacks,' Homer swings an axe at the water softener, making three large dents. The shot changes and one of the dents near the bottom vanishes. (00:13:30)
Continuity mistake: When Bart is digging his hole, Homer goes over and starts talking to him, and you can see a spade standing up outside of Bart's hole. The spade wasn't there in the previous shot of Bart digging. (00:02:05)
Continuity mistake: When Homer gets out of the electric chair, the sponge has disappeared from on top of his head.
The Bart Wants What It Wants - S13-E11
Other mistake: Ned Flanders wins the $100 bill, but on the side it says $50.
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.
Weekend at Burnsie's - S13-E16
Other mistake: When Homer gets a promotion from Mr. Burns, the latter's left eye is drawn such that it overlaps his nose. (00:11:30)
Tree House of Horror XII - S13-E1
Continuity mistake: In "Wiz Kids", when Milhouse is performing his trick at Springwart's Magic Recital, the trick goes wrong and he runs off naked, leaving his cloak on the floor. Later on in the scene, the cloak disappears.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when Homer attacks the tank, he puts the axe in the right hand side of the tank, but in the next shot the axe is now in the middle of it.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.