Treehouse of Horror XIII - S14-E1
Trivia: In the sketch where Homer clones himself, when he leaves the clones out in a cornfield and they learn to clone themselves, the camera pans right and amongst all the clones we see Peter Griffin, a character on the animated show Family Guy.
Treehouse of Horror XIII - S14-E1
Trivia: One of the Homer clones in "Send in the Clones" is the Homer from the early Tracey Ullman shorts.
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.
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