The Nightmare After Krustmas - S28-E10
Continuity mistake: While Krusty is in the hospital talking to Sophie, he pops the IV line from his arm so the tubing hangs down from the fluid bag. But when Krusty tells Sophie that he knows she's reaching out, suddenly Krusty's IV line is properly inserted in the cannula again, only to change back to the tubing hanging down. Also, the white pillow propping up Krusty's foot vanishes and reappears during these shots. (00:05:15)
The Nightmare After Krustmas - S28-E10
Continuity mistake: When Homer moves Maggie's crib closer to the gnome, the wall outlet under the light switch has nothing plugged in, but in the next shot as Homer exits the bedroom, a nightlight is suddenly plugged in. (00:10:20)
The Nightmare After Krustmas - S28-E10
Continuity mistake: When Krusty is in the hospital, the style of his bed rail changes. (00:04:20 - 00:05:35)
Continuity mistake: After Homer reveals the secret ingredient, one week later, Homer walks into Moe's. In the exterior shot, the door swings open at its right. However, when Moe lights the Flaming Homer, in the next exterior shot, the door swings open at its left. (00:21:00)
The Trouble With Trillions - S9-E20
Continuity mistake: The To Do Pile doesn't appear until Marge mentions it.
Postcards from the Wedge - S21-E14
Continuity mistake: When Lisa is talking to Bart in her room, Lisa's necklace is red rather than white when Bart shouts "End all life on this planet!" (00:08:05)
Continuity mistake: The position of the video in the basket changes between the first two consecutive shots. (00:04:50)
Continuity mistake: The position of the dots on Homer's pool change position. In the close up they're not near the water line but in the long shot they are. (00:03:10)
Continuity mistake: When Homer leans back the lamp next to him changes from a red freestanding one to a blue table-top one. (00:02:40)
Continuity mistake: Lionel Hutz runs out of Burns' office leaving both doors open. When Marge says about going, they are closed. (00:20:20)
Revealing mistake: When Grandpa is reading from the book trying to find out what is wrong with Maggie, the pages are blank. (00:09:30)
Continuity mistake: When Homer is talking about Marge getting a job at the dinner table he has a spoon in his hand. Once Marge has finished scowling he doesn't, and there isn't one on the plate either. (00:08:05)
Continuity mistake: We see the items fall off the roof but a Christmas ornament is not among them. However one lands on the ground with everything else. (00:02:05)
Continuity mistake: When stuff is falling off the roof, in the long shot there is nothing on the roof but in the close up there is. (00:02:05)
Itchy and Scratchy: The Movie - S4-E6
Revealing mistake: When Lisa is trying to explain to Homer about Bart seeing the movie, one of the pearls on her necklace keeps disappearing and reappearing. (00:18:20)
Itchy and Scratchy: The Movie - S4-E6
Continuity mistake: When Homer is about to punish Bart, his ticket suddenly appears in a shirt pocket. (00:15:10)
Itchy and Scratchy: The Movie - S4-E6
Continuity mistake: What the goats are eating changes depending on the shots. (00:10:10)
Itchy and Scratchy: The Movie - S4-E6
Continuity mistake: Homer asks Bart if he took the bins out. When Homer walks into the kitchen, the time on clock changes. (00:10:00)
Tree House of Horror III: The Simpson's Halloween Special III - S4-E5
Continuity mistake: When Homer finds out the doll is trying to kill him, the popcorn moves from the sofa onto his lap. (00:04:40)
Homer Alone - S3-E15
Continuity mistake: When Marge has finished the list of things to do at Rancho Relaxo she has a list on the bed. When we next see Marge a few seconds later, the paper is gone. (00:17:50)
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.