Kamp Krusty - S4-E1
Trivia: At the end of the show, the person singing 'South of the Border' is actually creator Matt Groening. Confirmed on DVD Commentary.
Kamp Krusty - S4-E1
Trivia: James L. Brooks, the executive producer, was so enthusiastic about the episode's premise that he wanted to make it the official Simpsons movie. This idea was abandoned because the writers had problems getting the story to 23 minutes, let alone 90 minutes.
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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