Homer's Triple Bypass - S4-E11
Other mistake: In the beginning of the episode when Chief Wiggum orders a battering ram through The Front door of a house, Reverend Lovejoy opens the door and questions what they are doing. Chief Wiggum says "isn't this 742 Evergreen Terrace?" to which Lovejoy replies that it's the house next door. In the next shot, you see Snake pulling out of the garage and speeding away. Everybody knows that 742 Evergreen Terrace is, in fact, the Simpson residence. (00:02:40)
Other mistake: When Lisa checks Marge's resume, she reads it and turns it over. But there is no text on the back as there should be. (00:06:30)
I Love Lisa - S4-E15
Other mistake: When Lisa and Ralph are swinging at the end, they are swinging outside the frame, but the swing is tied at the top of the inside of the frame.
Other mistake: When Homer is crossing the rickety bridge in the snow plow there is no snow on the planks even though he is in a blizzard and the storm couldn't have just started because the path he just came from was covered in snow. (00:18:55)
Krusty Gets Kancelled - S4-E22
Other mistake: When the Red Hot Chili Peppers are performing on Krusty's TV special, bassist Flea is playing a standard electric guitar.
Other mistake: When Moe is running to the Simpsons' house there is a shot of him running past the moon. When running back to the bar, the same shot is used but is simply flipped. Note the house and rocks. (00:18:20)
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
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)
Other mistake: When Homer pretends to read the newspaper, the back page is very noticeably blank and missing any print. (00:08:00)