Continuity mistake: When Bart crashes at the social club, his skateboard changes position between shots. (00:05:30)
Continuity mistake: During the Itchy and Scratchy cartoon, things change about the positions of the cats, the clothing, etc. (00:07:55)
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)
Continuity mistake: Bart's bruised eye has healed by the time he reaches Skinner's office to lick envelopes. (00:02:40)
Continuity mistake: When Skinner gets trapped under the papers, the jars on the shelves change color between shots. (00:19:15)
Continuity mistake: When Skinner is set free, while holding onto the vacuum, he changes position between shots. (00:20:15)
Continuity mistake: In the beginning, when Bart finds that the dog ate his homework, the poster on Bart's door has disappeared for one shot. (00:01:45)
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)
Continuity mistake: When Bart crashes at the door of the Legitimate Businessman's Social Club, his head is facing the door. You can only see this for several frames. In the next shot, his head is facing the sky. (00:05:25)
Continuity mistake: When Bart arrives home after his bad day, he is seen wearing his lucky red hat. It was never visible anywhere before he got home. (00:07:10)
Continuity mistake: When the pile of newspapers fall on principal Skinner, two garbage cans appear out of nowhere beside the door. (00:19:10)
Continuity mistake: When Bart finds out that Homer took the police badge out of the cereal box, it changes from brown to pink. The food inside the box also changes to pink. (00:01:10)
Continuity mistake: When Homer is gambling with the gangsters, you can just barely see the shoulder of an ORANGE shirt that Bart is wearing, but in all other shots he is wearing his tuxedo. (00:12:10)
Continuity mistake: Bart's drawing of Principal Skinner is gone when Mrs. Krabappel says that he is missing. (00:14:05)
Continuity mistake: When we see Skinner's car before the newspapers fall on him, it is a light-brownish color. When the police arrive, it is the same color as the cop cars. (00:19:10)
Continuity mistake: In the beginning, Bart's bedroom's window faces the backyard. When the bus leaves, it faces Evergreen Terrace. At the beginning of Bart's nightmare, it faces the backyard again. (00:00:55 - 00:15:45)
Continuity mistake: There are three mistakes when court is dismissed: 1) the people standing around disappear, 2) the two men with Fat Tony disappear for one shot, and 3) when Bart says that crime doesn't pay, Marge is suddenly standing beside Bart. (00:20:35)
Suggested correction: There are also 3 corrections here. 1) the only people standing near the bench are Lionel Hutz and Seymour Skinner. Seymour is simply out of shot and Hutz is on screen. 2) Legs and Louie don't disappear they remain standing on the steps but due to the camera angle that is now looking across the steps rather than up the steps so they are out of shot. 3) There is a close up of Bart and Fat Tony long enough for Marge to walk over.
Continuity mistake: Bart puts his lucky red hat on the hat holder. It disappears in the next shot. (00:07:10)
Continuity mistake: When Bart realizes he forgot his permission slip, the camera shows us that the paper is half-under his pillow. However, when he got out of his bed at the very beginning, the paper wasn't under his pillow. (00:01:00 - 00:03:05)
Continuity mistake: When the newspapers fall on Skinner, the rake in the corner has turned into a shovel. (00:19:10)