Continuity mistake: When Homer shows up to the Bouvier home the night of the prom, Selma and Patty open the door and it opens outward, but in the following shots the door has been opened inward. (00:16:10)
Continuity mistake: After Homer's emotional outburst about the lack of bananas, when it cuts to the exterior shot of the Lovejoy house the doorknob is on the right side of The Front door, but when Reverend Lovejoy kicks Bart out of his house, the doorknob is on the opposite side. Later, when Jessica twirls the baton, the doorknob is on the right side again. (00:08:00)
Continuity mistake: When Marge runs after Bart because he's hiding something under his jacket, Homer pulls out a gate to block Bart's entrance to the TV room. Three different gate styles are shown. (00:20:35)
Continuity mistake: In some shots Otto's beaded bracelet vanishes and reappears, such as when he's on the school bus before the accident. Also, note a watch suddenly appears on his left wrist then it disappears, on the school bus. (00:11:05 - 00:15:15)
Continuity mistake: While Otto plays the guitar at 3:00 AM, the tuning keys on the guitar head are first facing down, then the guitar head flips and the tuning keys are facing up, between shots. (00:15:45)
Continuity mistake: When Homer is wearing underwear while banging on the bathroom door the doorknob is missing, but next shot it appears on the door, and the closet door hinge also vanishes. (00:18:25)
Continuity mistake: When Otto's guitar playing wakes Marge and Homer they go to the garage. Note the direction of the door when Homer opens it toward the right, but when Marge asks Bart what's going on, the door's open the opposite way toward the left. (00:15:55)
Continuity mistake: When Marge comes downstairs she's shocked to see Homer in her house, and when the doorbell rings we see Mrs. Bouvier wearing an orange belt with a red buckle, but then the colors switch to an orange buckle and the belt center is red. (00:16:45)
Continuity mistake: When Homer stands outside the Bouvier house to pick up Marge, the home's front door has three diagonal windows from upper left to lower right. However, when Marge gets home later after the prom, the three windows are diagonal the opposite way from upper right to lower left. (00:16:10 - 00:21:00)
Continuity mistake: When Ned stops to snap at Lisa he's already yelled at Marge and Bart. Yet in the background you can see Marge among the secondary characters.
Continuity mistake: When explaining RDRR, Ms. Mellon writes "y=r^3/3" on the board behind her. But after she asks, "Don't you get it, Bart?", the equation disappears from the board and she writes it again.
Who Shot Mr. Burns? (2) - S7-E1
Factual error: Chief Wiggum visually compares a bullet taken from Homer's gun to the bullet removed from Burns and concludes that they are exactly the same. Excluding the obvious forensic violation, the bullet removed from Burns is still whole and within its casing, meaning that either Maggie took the time to remove the casing and delicately shove it in Mr Burns' bullet wound (which is dumb) or the gun fired the whole casing along with the bullet (which would have blown up the gun).
Mothers and Other Strangers - S33-E9
Continuity mistake: A teenage Homer and his father travel to Utah to look for Homer's fugitive mother, whom they find. This completely contradicts the episode Mother Simpson, where Homer didn't reconnect with his mom until he was in his late thirties, and was told all his life by his father that she was dead, even believing that the grave of Walt Whitman belonged to his mother.
Continuity mistake: In the scene at the United Nations, the Russian placard is just a placard. In the next shot, the placard is attached with a rod to rotate it at the push of a button.
Homer's Triple Bypass - S4-E11
Continuity mistake: When we first see Krusty start talking to Homer, from the rear shot you can see Krusty is missing his pale colour on his face. However, in every other shot, his pale complexion is there. (00:15:10)
Homer's Triple Bypass - S4-E11
Continuity mistake: When we see Lisa in Sunday school, the colour chair she is sitting on changes from blue to brown as she talks about her dad being very sick. (00:14:40)
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)
