Strong Arms of the Ma - S14-E9
Audio problem: The speech does not match the lip movements from when Bart says, "dad, do you plan to get in shape?" until Lisa says, "Uh guys, mom just left the basement." (00:12:17)
Strong Arms of the Ma - S14-E9
Audio problem: When the piano is playing Fur Elise, the keys do not move.
Strong Arms of the Ma - S14-E9
Audio problem: When Marge sprays the pepper spray at Ralph, the line she says after does not match her mouth.
Strong Arms of the Ma - S14-E9
Audio problem: When Homer says he'll eat twice as much, Bart says excellent, but that doesn't match his mouth.
Strong Arms of the Ma - S14-E9
Audio problem: When the woman who smashes the piano says "support the arts", her mouth is open, but it doesn't move.
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