The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: When Homer finds out that he has no Christmas bonus the background behind Marge is the kitchen, but then it cuts to Homer and the background behind him is the kitchen too. (00:08:20)
Tree House of Horror VII - S8-E1
Continuity mistake: In 'The Genesis Tub,' Lisa sits on a tooth-throne in the tub, which has red cloth draped over the arms with gold tassels around the edge. However when Bart comes to take the tub, Lisa stands up on the throne and yells "Bart, no!" In this shot the tassels are gone. (00:17:45)
Hamster
Continuity mistake: When Sideshow Bob is shouting and screaming just before he is taken away in a police van, Lisa and Bart swap places right before Bart says "Take him away, boys."
There's No Disgrace Like Home - S1-E4
Other mistake: When Homer is at Moe's, there is a boxing match happening on TV. There is a bald guy who is getting considerably battered by the opponent and gets knocked out, and then for some absurd reason he is victoriously standing and smiling as if he had won.
OL1V3R666
Revealing mistake: When there is a zoom in of the house just before Bart gets up late, it has the old arch-shaped windows, but in the rest of the episode it has the normal windows. It's obviously a screen from Season 1. (00:06:00)
OL1V3R666
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: During the family's breakfast, in most shots Marge sits right beside Maggie's highchair, but in certain close-ups they are quite a few feet away from one another. (00:05:25)
Super Grover 
Continuity mistake: When we first see Homer feeding the can to the goat the background shows a wooden coop. In the next shot, a purple tree stump appears there too.
Continuity mistake: During the Itchy and Scratchy cartoon, things change about the positions of the cats, the clothing, etc. (00:07:55)
YoshiSuggested correction: This is a cartoon within a cartoon. Things do not always have to be 100% correct.
Continuity mistake: When we first see the papers on top of Skinner, the jar of preserves is not visible anywhere. It is beside him in the next shot. (00:19:15)
Yoshi
Continuity mistake: Bart's bruised eye has healed by the time he reaches Skinner's office to lick envelopes. (00:02:40)
Yoshi
The Call of the Simpsons - S1-E7
Continuity mistake: When the bear first confronts Maggie, she is on a path. Yet in the next shot when the bear lands on the ground, she is on grass. (00:11:15)
Migster
Continuity mistake: When Bart is explained the answer RDRR, there is a shot of him. There is a blue background where the classroom should be.
OL1V3R666
Tree House of Horror XII - S13-E1
Continuity mistake: In the end credits when the stars exit the caravan, there is a wooden step under the door of the caravan. However, when they climb into Pierce's car and drive off, the wooden step is gone. (00:20:55)
Hamster 
Realty Bites - S9-E9
Continuity mistake: When the real estate team learn that Marge has sold the murder house, Marge is wearing a red blazer but in the shot which faces Marge's back the blazer is missing, then in the next shot Marge is wearing the blazer again.
Continuity mistake: After Homer prepares the BBQ he holds out the steak and holds it back in as Lisa speaks. When the shot changes he's holding it out again, and the pile of meat behind him is smaller and has moved slightly under the window.
Continuity mistake: When Lisa is first seen petting the baby lamb, she is next to the fence with hay beside her. In the next shot, she's far away from the fence and there's no hay anywhere.
Continuity mistake: Throughout the dinner scene, whenever Homer wants the syrup, it disappears and re-appears next to Lisa.
Continuity mistake: When the mobsters enter Skinner's office, the phone on his desk changes position between shots. Also, the name bar on his desk doesn't read anything on it. (00:13:50)
Yoshi
