Continuity mistake: After Bart is sent to Maison Derierre, he knocks on the door. Belle answers it and for a couple of frames her arm is naked. Then suddenly her corset appears on her arm.
The Springfield Files - S8-E10
Continuity mistake: At the kitchen table, when Homer talks about getting mocked on his own birthday, they're eating breakfast. But when Marge, Lisa, Bart and Maggie all go to pet Santa's Little Helper, the breakfast has vanished.
Simpsons Spin-off Showcase - S8-E24
Continuity mistake: In Moe's spin-off, just before Barney leaves the bar, his beer glass vanishes.
Lisa's Date with Density - S8-E7
Continuity mistake: Whilst Chalmers notices the Honda symbol missing from his car, there are four holes in the corners of the leftover symbol. There is a screw in one of the holes indicating the symbol would have holes in its corners to hold it down. Later when Skinner finds the Honda symbol in Nelson's locker you can see there are no holes in the symbol.
Continuity mistake: When Santa's Little Helper is taken away by the Repo Men, the van's back bumper is first seen to have no number plate. When the van drives off, there is a number plate.
Tree House of Horror VII - S8-E1
Continuity mistake: In 'The Genesis Tub,' when Skinner is grading the universe in the tub, his clipboard changes from brown to blue. (00:17:55)
The Springfield Files - S8-E10
Continuity mistake: When the 'alien' is seen on the news, it is shown on the film Bart made coming out of the trees, but earlier on, when the alien came out of the woods, Bart is seen not holding the video camera.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Continuity mistake: During the song "Its the American Way" Snake is robbing Hans Moleman during Chief Wiggum singing and Snake's hair is blue. His hair has always been a brown-red color. In the very next scene to confirm its a mistake you see him in the park saying "Yo Sherry Bobbins" and his hair is back to its brown-red color.
The Secret War of Lisa Simpson - S8-E25
Continuity mistake: When Lisa and Bart are practising for the 'Eliminator', Lisa doesn't have a rope round her waist, but when she falls she does.
Simpsoncalifragilisticexpiala(Annoyed Grunt)cious - S8-E13
Revealing mistake: When Dr Hibbert is examining Marge's hairs (and I think another time in the episode), some holes are too low and you can see through her head.
Continuity mistake: The "Stinger" only appears on the boxing gloves after Moe passes them to Homer. It is not there in all preceding shots.
The Secret War of Lisa Simpson - S8-E25
Continuity mistake: When Lisa climbs to the top of the Eliminator, there is a platform for her to stand on. Strangely in the next shot Lisa is standing on nothing so she appears to be standing in mid-air.
Continuity mistake: When the Simpsons are driving to Cypress Creek the arrangement of luggage on the roof of the car changes depending on their stage in the journey.
Lisa's Date with Density - S8-E7
Continuity mistake: The hole in Nelson's locker increases in size.
Continuity mistake: When the angry mob smash all the statues and the fountain before the song, during the song you can see all the statues and the fountain intact.
Tree House of Horror VII - S8-E1
Continuity mistake: In "The Thing And I", Bart discovers he has a scar where he was separated from Hugo. During the attic scene, it disappears. (00:04:40 - 00:06:10)
Continuity mistake: The extension cord Jimbo is using for a belt disappears after they run around the corner of the corridor whilst chasing Bart.
Continuity mistake: When Homer is walking and talking with Hank Scorpio when he first arrives at work there is reversed "J" on Homer's tie that comes and goes between shots.
Continuity mistake: When Marge goes to see Belle at the Maison Derriere she sits down with her.At first there is a white ornament on the small table in front of them but then at the end of the scene it has vanished.
Continuity mistake: In the beginning, the family is eating in front of the T.V. When Marge is complaining about getting the food all over the floor, she drops her meatball on the floor, and it leaves a trail of sauce on the rug. In the bird's eye view of the room, the sauce has disappeared until the shot changes: then it reappears.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.