Homer vs. Patty and Selma - S6-E17
Chief Wiggum: Evening, Simpson. You got a short in your taillight, started blinking when you made that turn.
Homer vs. Patty and Selma - S6-E17
Bart: What a day, eh, Milhouse? The sun is out, birds are singing, bees are trying to have sex with them - as is my understanding.
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