Papa's Got a Brand New Badge - S13-E22
Continuity mistake: When the family is sitting on the couch and trying to catch a breeze from the fan, Lisa's shoes disappear between shots.
Papa's Got a Brand New Badge - S13-E22
Continuity mistake: When Homer goes to the cupboard, there are no wires to the right of it. However, when Homer plugs in the singing Santa, there are lots of wires trailing to the right. (00:02:40)
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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