Continuity mistake: When Marge is telling Homer off about staying in the car she has gloves on. Camera changes to her saying "Move it" and now her glove has disappeared. Her hand also moves from being on the door to pointing. (00:05:00)
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Marge is making peanut butter sandwiches in the kitchen, she has already made one sandwich and there is one slice of bread by the peanut butter jar. When Homer walks up to Marge, another slice of bread appears.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Bart is eating a doughnut when talking to Lisa in the bus, the apostrophe on "Comic's" in his bag keeps disappearing and re-appearing between shots.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Marge reads Jacques' bowling ball, it says "Brunswick." Later on in the episode, it reads "Jaques" (spelt incorrectly).
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Marge comes home and finds Homer sleeping in bed, the alarm clock next to Homer is initially facing straight but in the next shot it is facing towards Homer.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Bart, Lisa, Maggie and Homer have finished eating their slices of pizza, there are initially four crusts left in the box. When Homer is holding the box a little later on, there are now only two crusts.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Jacques tells Marge to throw the ball at Barney's Bowlarama, you can see behind Marge there are some green seats, but in a close-up of Marge in the next shot, a red chair suddenly appears.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Jacques picks up Homer's bowling ball, you can see the ball by Jacques' right hand on the rack next to him is coloured green. When we see a close-up of Homer's bowling ball in the next shot, the ball is red.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: After Marge has put on her bowling shoes, she throws the bowling ball and you can see that the ball is aiming for the pins in Lane 10. When we see a close-up of the pins in the next shot, they are now in Lane 9.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Marge is speaking to the man behind the counter at Barney's Bowlarama, the word "Homer" can be seen above the three holes on her bowling ball. When the man says that she can't bowl without a lane, the word has disappeared, and in the shot after that, it is back again.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When the bowling ball has fallen onto Marge's birthday cake, there is a candle on the table that changes position when Homer and Marge are talking.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Homer says that Marge hasn't opened his present yet at her birthday dinner, there is a plate and glass in front of him on the table. But then the waiters come over to the Simpsons' table in the next shot, look at Homer and you can see that the glass and plate have disappeared.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Homer says "Hold on!" during Marge's birthday dinner, look at his plate and you can see that his fork has been replaced by another knife.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When we see Homer eating at Marge's birthday dinner at Singing Sirloin, there is a cake on a dish and a wine glass by his plate. When we see Homer a little later on, the cake and wine have disappeared and there is now an ordinary drinking glass by his plate.
Life on the Fast Lane (a.k.a. Jacques to Be Wild) - S1-E9
Continuity mistake: When Homer opens the door with his present, look at the door knocker and you can see that is a completely different one to the one seen at the start of this episode.
There's No Disgrace Like Home - S1-E4
Continuity mistake: When undergoing shock therapy, the doc raises his hands to his head. They are not present in the next shot. (00:19:00)
There's No Disgrace Like Home - S1-E4
Continuity mistake: When Homer walks in on the family eating dinner, Marge has her feet on the second cushion of the sofa. Camera changes and now they are on the third cushion. (00:08:50)
There's No Disgrace Like Home - S1-E4
Continuity mistake: When they put Maggie down in the Creche she is in the middle of a carpet. Camera cuts and now she's at the edge. (00:04:25)
There's No Disgrace Like Home - S1-E4
Continuity mistake: The amount of marshmallows in the jelly at the start changes between shots. (00:02:00)
Continuity mistake: On the bus at the start there are some lines on Mrs. Krabbapple's microphone. They disappear when she tells Bart to sit down. (00:03:00)
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