Continuity mistake: After Homer falls asleep at the wheel the truck starts to turn the corner. As its going around the bend you can see a white line on the road. The following shot the line has disappeared.
Continuity mistake: When Lisa finds the doorbell Marge wanted and she plays it, it is gold, but when Marge picks it up it is grey-ish.
Continuity mistake: When Red has finished the steak, he lies back and is the same position for Homer's small speech. However, as soon as Homer starts to say 'Wait, you're not breathing,' Red blinks when he is meant to be dead.
Audio problem: When the radio is playing "Wannabe", the song stops but Homer doesn't touch the radio.
Simpsons Bible Stories - S10-E18
Other mistake: Rev. Lovejoy is reading Genesis, the first book of the bible, but he is a good way into the book. Surely it would be at The Front?
Simpsons Bible Stories - S10-E18
Continuity mistake: Homer as Solomon cuts the pie into a roughly 1/3 and a 2/3 piece, but when he picks the pieces up, it's more or less halved.
Simpsons Bible Stories - S10-E18
Plot hole: Somehow, despite being enslaved and being nowhere near anything that could help them, the Jews have a camel, which we did not see coming across the channel.
Simpsons Bible Stories - S10-E18
Continuity mistake: When Bart is trying to wake up Homer, Maggie is seen with a blue pacifier. In the shot after the next, Maggie's pacifier is red.
The Old Man and the C Student - S10-E20
Continuity mistake: Springy the Olympic spring that Homer makes has 9 coils. Then we see the large version that has many coils, at the Olympics meeting. Homer's original spring is in his hand and now it has many coils also. When it cuts back to the stage, the large spring has few coils, like the very first time we saw Springy.
The Old Man and the C Student - S10-E20
Continuity mistake: The springs on Homer's hat change size when Agnes answers the door to him.
The Old Man and the C Student - S10-E20
Continuity mistake: When Homer offers Lenny some nuts a spring pops out and gets Lenny in the left eye, but the next time we see Lenny it is in his right eye.
The Old Man and the C Student - S10-E20
Audio problem: At the choir at the start, Lisa's lips don't move when she says "oh no."
The Old Man and the C Student - S10-E20
Audio problem: At the end of the episode, Grampa's mouth doesn't move when he sings.
Monty Can't Buy Me Love - S10-E21
Continuity mistake: Ralph Wiggum is seen riding the train inside the mall, but is seen some seconds later amongst the crowd of people still waiting to enter the store.
Monty Can't Buy Me Love - S10-E21
Continuity mistake: Bart is next to Homer when Marge says "Where did you get that champagne?", but in the next shot, a clown is in the spot Bart was.
They Saved Lisa's Brain - S10-E22
Character mistake: The plural form of ignoramus is ignoramuses, not ignorami. The word "ignoramus," a Latin verb-form meaning "we do not know," has no Latin plural-noun form. Therefore, when used as an English noun it correctly pluralizes as "ignoramuses." Someone as smart as Lisa should know this.
Thirty Minutes Over Tokyo - S10-E23
Continuity mistake: Marge loses one of her shoes in the "lava" , but when they fall down, Marge wears two shoes again.
Thirty Minutes Over Tokyo - S10-E23
Continuity mistake: When Homer breaks into Flanders's house there's a shot of the refrigerator and nothing is on it. In a closer shot, there are tickets being held up by a magnet.
Thirty Minutes Over Tokyo - S10-E23
Factual error: There is a flight to Honalulu, Hawaii listed on the national flights screen. This is a domestic flight, as it does not involve leaving the country.
Thirty Minutes Over Tokyo - S10-E23
Continuity mistake: When Database is at The Java Server, he is using a teal computer, but when Snake comes in, he is using an orange computer, then he is using a teal computer again.
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