Plot hole: The director of Radioactive Man says to Bart "we found our new Fall Out Boy. That's what I would say if you weren't an inch too short. NEXT!" But Milhouse is the new Fall Out Boy, and he's blatantly smaller than Bart. Bart was standing right next to Milhouse, so the director could see the difference.
Treehouse of Horror XXI - S22-E4
Continuity mistake: In the second segment, after Roger has told them about what happened to him, a radio appears out of thin air.
Treehouse of Horror XXI - S22-E4
Continuity mistake: In the second segment, as Roger is telling them about what happened to him, as he finishes the story of Marge and Homer saving him, in his recount Marge is wearing a shirt and bikini bottoms (the shirt is covering the bikini bra). But when they saved her, she was just wearing a bikini.
Continuity mistake: Burns is interrogating Homer after giving him drugs. He asks him to speak into a lamp with a microphone in it. The lamp disappears when they're done.
Cape Feare - S5-E2
Continuity mistake: When the Simpsons get out of the car at Terror Lake, there are no rakes on the ground. When Bob gets out of the car, there is a whole stack of them. (00:14:30)
Continuity mistake: When Homer is in Moe's, Moe pours him a full pint. When it's passed to Homer, it's now 3/4 full in the glass. (00:10:40)
Continuity mistake: At the start, Homer has his feet on the floor until Ruth asks for a sander, and one suddenly appears under Homer's feet. (00:02:30)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: In Terror at 5 1/2 Feet, as Bart is being stretchered away, he is sat up on the stretcher, but when Skinner says, "perhaps a life at the mad house..." Bart is now lay down. (00:14:05)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: In Terror at 5 1/2 Feet, just as Millhouse is getting ready to move seats, he's sat with his hands in his lap until the shot changes, and then he is holding a red book. (00:12:00)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: In Terror at 5 1/2 Feet, the size of the notepad above the phone changes several times. (00:09:30)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: In Terror at 5 1/2 Feet, when Bart gets scared by Homer, there is a spare bowl on the table right next to his. When the shot changes, this spare bowl has disappeared. (00:09:30)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: In Terror at 5 1/2 Feet, Bart throws his spoon when Homer blasts the air horn. When the shot changes, the spoon has reappeared in the bowl. (00:09:30)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: In Terror at 5 1/2 Feet, Bart has a nightmare and walks into the kitchen, and there is no bowl in front of him. When Lisa speaks, a bowl appears in front of Bart. (00:09:10)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: When Homer is being taken to hell, his position in the floor keeps changing. Note the tile patterns. (00:03:40)
Tree House of Horror IV: The Simpson's Halloween Special IV - S5-E5
Continuity mistake: When Homer finishes his donut, the number of bits of paper on the fridge changes from 3 to 4. (00:03:20)
The Fat and the Furriest - S15-E5
Continuity mistake: When Homer and the bear face each other in the cave, he's barefoot, but when he removes the electric prod from the bear's ear, he inexplicably wears shoes, and then he's barefoot again when he puts it on his ear.
Continuity mistake: When Bart runs his nails down the chalkboard, the image on the board changes slightly; note the legs. There is a gap between one leg and the body in one shot, but not the other. (00:14:00)
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.