Continuity mistake: When Lisa is watching tapes of Francine's bullying, there is a scene where they are at the pool. Francine is wearing nose clips in this scene. But when Lisa freeze-frames and leans in to closer inspect the shot, Francine's face is shown on the screen without nose clips. They appear again when Lisa exclaims "Of course. The nose clips."
Continuity mistake: When Bart is eating the grubs, his tongue appears to be green, in all other shots it's back to red.
New Kids on the Blecch - S12-E14
Continuity mistake: When L.T.Smash sees his admiral, we see he his has badges on, yet when the shot changes and zooms in on him, they're gone, then they're back. (00:17:10)
Continuity mistake: When Marge is racing the school bus, as the bus jumps out of the ditch you can see that the bottom of the bus is painted to resemble a skateboard. When the bus lands from this jump, however, the bottom of the bus is an even grey colour.
Continuity mistake: During Tom Savini's presentation, the comic book seller eats a kind of cookie. Fake blood then start to flows from his mouth and he takes his t-shirt to wipes it. There are no stains on it after that.
Skinner's Sense of Snow - S12-E8
Continuity mistake: When the Hamster rolls through the glass of Flanders car it breaks it near the bottom middle of The Front windshield. Later on when Flanders and Homer are taking the kids home you can see the break in the glass has now moved to about halfway up The Front windshield. On of the following shots it moves back to its original position and then moves back to being around the middle of the windshield.
New Kids on the Blecch - S12-E14
Continuity mistake: When L.T. Smash switches the lever to Commission from De-Commission, after that, when the shot changes, it says Ship and Museum. (00:18:10)
Continuity mistake: When Bart is trapped in the coffin, the cables leading to the Cadaver Cam TV disappear then reappear. (00:04:10)
I'm Goin' to Praiseland - S12-E19
Continuity mistake: When we first see the "Whack-a-Satan" game at Praiseland, there are three rows of holes the little devil dolls emerge from. After Nelson turns towards Flanders, the game is seen behind him, now with only two rows of holes.
Continuity mistake: When Comic Book Guy turns off the water hydrant, the two boys in purple and blue trunks change position between shots.
Continuity mistake: When the Simpsons are at the restaurant at the start, Bart has no medal on his jacket. But when Lisa remarks a few seconds later that Homer gave Bart a medal, one has appeared on his jacket.
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 the Simpsons are on the raft going down the river in Africa they come to a fork and have a choice of going to the left, towards a sunny and nicer area or to the right where it is rainy and gloomy. As Homer tries to steer the raft to the left as he pulls his left arm out of the water and it is covered in leeches but in the next shot of him when we see the arm again the leeches are gone. No way to remove leeches that fast.
Skinner's Sense of Snow - S12-E8
Continuity mistake: When Skinner dismisses the kids from school, we learn the snow level is near the top of the windows and to the top of the doors. But in the next scene, we see a shot of Springfield and the Simpson home, where the snow level is to the bottom of the door. (00:08:02)
Continuity mistake: The bikes disappear after Bart and Milhouse arrive at the cave.
Continuity mistake: When Homer is eating the sausage, a square on his shirt disappears in a shot from his feet and then is back in the next shot.
Continuity mistake: When Lisa comes and starts giving out apples, Moe is seen taking one of them, but some seconds later, he is seen under Homer's coat with a piece of Homer on a fork.
I'm Goin' to Praiseland - S12-E19
Continuity mistake: Helen Lovejoy suddenly has lipstick on when she gives Homer the ice cream. She doesn't have lipstick on in previous shots.
Continuity mistake: Lenny's mug refills itself when he tells Homer, "You want to help me?"
Continuity mistake: After Amy Tan shames Lisa, there is a shot of Lisa wearing a red necklace, her necklace becomes her usual white one, seconds later.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.