The Old Man and the Key - S13-E13
Homer: Here we are: Branson, Missouri.
Male Charles Bronson Lookalike: No, pally. This is Bronson, Missouri.
Lisa: Well how do we get to Branson?
Female Charles Bronson Lookalike: Number 10 bus.
Child Charles Bronson Lookalike: Hey Ma, how 'bout some cookies?
Female Charles Bronson Lookalike: No dice.
Child Charles Bronson Lookalike: This ain't over.
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