Skinner's Sense of Snow - S12-E8
Factual error: Superintendents are the ones who decide whether or not schools should be closed for snow days, not school principals.
Skinner's Sense of Snow - S12-E8
Continuity mistake: When the children are sleeping in the canteen at school, Bart is resting his head on a red sweater. In the close up of him and Lisa, the sweater has now turned dark green. It's not because of the dark that we see it like that because there is a bit of light at the beginning of the next shot and we see the jumper to be dark green.
Skinner's Sense of Snow - S12-E8
Audio problem: When Principal Skinner is watching the kids throw the books in the fire, someone goes to throw Huckleberry Finn into the fire. He says "Not Huck Finn. I spent hours crossing out the sass-back." While he says this, his lips don't sync with the words.
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.
Continuity mistake: When Homer sits down in the movie theater, all the rows are completely full, including the row behind him. When he turns around to talk to Selma, the seats directly behind him are empty. Then, when Homer turns back to the screen, the Sea Captain and Dr. Hibbert appear sitting directly behind him.
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.
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 Bart is trapped in the coffin, the cables leading to the Cadaver Cam TV disappear then reappear. (00:04:10)
Continuity mistake: In the very beginning of the episode, Bart places Santa's Little Helper's dish into the sink and begins playing with the faucets. Marge comes in, and the bowl magically disappears from the sink, and it's missing for the rest of the scene.
New Kids on the Blecch - S12-E14
Continuity mistake: When Bart and the group are singing at school, when we see L.T.Smash, his arms are down then instantly in the next shot, they're on his sides. (00:08:10)
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)
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)
New Kids on the Blecch - S12-E14
Continuity mistake: When Homer is pinching Lisa with the "jealousy bug", the sign behind him changes from a gift store to an antique store.
New Kids on the Blecch - S12-E14
Audio problem: When the VJ on the TV says "That was the latest ad from Stridex pads. Medicated", her mouth is terribly out of sync with her voice.
Continuity mistake: When Homer sees the hotdog that Duffman holds up near the end of the episode, the order of the condiments on the hotdog change in subsequent shots.
Continuity mistake: Before Homer sees his vision of Caesar Romero the day sign next to him says 9. After the Duff executives see him talking to nobody they decide to take him away and when they get down there the sign now says 12 with the president of Duff confirming it in his speech. Doubtful it took them 3 days to get down to him and not much reason for Homer to take 3 days off the sign seeing as he was almost passing out from the lack of food.
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.
Other mistake: When Lisa says Bart's got a girlfriend, Bart says "no, I don't, that's the problem", his neck becomes longer and starts to wobble, a problem with the animation.
Continuity mistake: Lenny's mug refills itself when he tells Homer, "You want to help me?"
Continuity mistake: When Marge is putting Lisa and Bart's clothes on, she puts Lisa's dress on Bart and Bart's shorts and t-shirt on Lisa, but 2 seconds later, when they are entering the kitchen, they are wearing their normal clothes.
Answer: I'm not sure if this is the one you're thinking of, but an episode of "Ray Bradbury Theatre," called "A Sound of Thunder," dealt with a similar matter: a group of hunters travel back in time to hunt dinosaurs, only to find things have changed when they get back because someone stepped on a butterfly.
Xofer