Continuity mistake: When the bottle of bourbon is found and taken out of Marge's pocket, the bottle is grey. But when Sanjay throws it to Apu, and Apu catches it, the bottle has now changed to a brown colour. (00:08:30)
Continuity mistake: When Marge comes to pay for her shopping, she empties her left pocket on her coat, but when Sanjay finds it in her pocket, it's in her left pocket. We know it wasn't in her pocket anyway because when Sanjay finds it, it is bigger than the size of her pocket.
Audio problem: At the end of the episode the statue of Jimmy Carter with Marge's hairdo is unveiled, and the assembled throng applaud her reaction. They are all chattering away, but no sound is coming out of their mouths - we only hear the sound of clapping.
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