Homer's Triple Bypass - S4-E11
Continuity mistake: When Nick gives the news about Homer's recovery, the books on the table next to Marge change between shots. (00:20:30)
Marge vs. the Monorail - S4-E12
Other mistake: When Homer crashes his car, he just disappears when it hits the tree. (00:01:50)
Marge vs. the Monorail - S4-E12
Continuity mistake: The Springfield forest is across the road from the school, but in many other episodes, it is somewhere completely different.
Marge vs. the Monorail - S4-E12
Continuity mistake: Mayor Quimby's suit changes from dark blue to purple throughout the whole town hall scene.
Marge vs. the Monorail - S4-E12
Continuity mistake: When Grandpa Simpson stands up in The Town hall, the position and amount of paintings on the wall change several times between shots. (00:06:10)
Marge vs. the Monorail - S4-E12
Continuity mistake: Throughout the whole town hall scene, people constantly change positions between shots.
Marge vs. the Monorail - S4-E12
Other mistake: Lanley's desk in his trailer suddenly gets brighter even though none of the lights in the trailer were turned on. (00:12:50)
Marge vs. the Monorail - S4-E12
Continuity mistake: Cobb's hair in North Haverbrook changes length between shots. (00:14:10)
Marge vs. the Monorail - S4-E12
Continuity mistake: When celebrities are coming to ride the monorail, the positions of people in the crowd changes positions between shots.
Tree House of Horror III: The Simpson's Halloween Special III - S4-E5
Plot hole: At the theatre in the "King Homer" bit, the audience are treated to a traditional showgirl spectacle. But the girls have no curtain behind them, and so the audience should have seen Homer the ape, but they act completely surprised a minute later when Homer comes on. (00:11:40)
Lisa's Pony - S3-E8
Revealing mistake: At the end, Homer and Lisa don't cast a reflection on the Kwik-E-Mart's doors. They should, since they are only a few metres from it.
Wild Barts Can't Be Broken - S10-E11
Continuity mistake: When Homer enters the bar, you briefly see that Lenny has dark green braces and a fawn coloured shirt. The next shot, they switch colours.
Wild Barts Can't Be Broken - S10-E11
Continuity mistake: At one point, Lisa and Bart are watching fireflies through the window. When Homer comes in, the fireflies are gone.
Wild Barts Can't Be Broken - S10-E11
Audio problem: When Lisa is broadcasting secrets about Springfield residents in a British accent, her lips don't match her mouth at all.
Sunday, Cruddy Sunday - S10-E12
Continuity mistake: When Homer gets the coupon book, look at the plant on the wall. It changes position between shots.
Sunday, Cruddy Sunday - S10-E12
Continuity mistake: The desk in the car repair shop behind Homer changes positions between shots.
Audio problem: At the end where Homer is carrying Mark Hamill out of the theatre, Mark's lips don't match with what he's saying.
When You Dish Upon a Star - S10-E5
Revealing mistake: When Homer and the family are having hamburgers at the dinner table, at one point you can see the oven. The pointer on one of the dials is misaligned.
Revealing mistake: When Skinner talks to Otto on the bus, the point of his hair is touching a pole. Look at the pole - Skinner's hair is going through it.
Bart Carny - S9-E12
Continuity mistake: When Cooder comes out of the house to witness Homer throwing the ring onto the chimney, there's a doorbell on the side of the doorway. The next shot, it's disappeared.