Continuity mistake: When Homer is gazing at the commercial on the television, Bart is beside him but there is no sign of Lisa. After a quick cut to the TV set, we return to Homer and Lisa is back again.
Continuity mistake: When the doctor brings the "Hair in a Drum" product from under his desk, you can see in front of Homer there is a bottle of Dimoxinil and two gravity boots. When we see a close of the product in the next shot, the bottle and gravity boots on the desk have disappeared.
Continuity mistake: When the doctor places the items that come with the Dimoxinil on his desk, he places the scalp massager next to the pad. When Homer asks the doctor how much, we cut back to the doctor and the scalp massager is now on the pad.
Continuity mistake: When Homer gets mad when Carl calls him "Chrome Dome", there is a fish stick on his plate, but in the next shot, the fish stick has disappeared.
Continuity mistake: When Homer is speaking to Carl and Lenny at the coffee stand, there is initially nothing in Lenny's cup, but a few shots later his cup is now full without him filling it.
Homer's Triple Bypass - S4-E11
Continuity mistake: When Homer begins praying, the room is dark and there is barely any light. When the nurse shushes him, suddenly it's a lot brighter. (00:14:20)
Homer's Triple Bypass - S4-E11
Continuity mistake: When Barney and Moe visit Homer, the vase of flowers disappears and then suddenly reappears at the end of the scene. (00:16:10)
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.
