Plot hole: In the last part of the episode, when Mr Burns is trying to convince Homer on his float to play a big prank, the timing is totally wrong. Firstly, Lisa sees the writing 'Happy Pranksgiving' on the side of Mr Burns' float way before it reaches her, and it takes Mr Burns ages to change into the Father Christmas outfit.
Deliberate mistake: The mouth on the panda costume is in a constant smile and at no point does Homer change it, even when he is in pain. However, when he is being pulled back under the curtain the mouth is open and the mask has a frightened expression. I suppose this was done on purpose, but it's still a continuity error of sorts.
Continuity mistake: When Skinner dismisses the kids from school, we learn the snow level is near the top of the windows and to the top of the doors. But in the next scene, we see a shot of Springfield and the Simpson home, where the snow level is to the bottom of the door. (00:08:02)
Continuity mistake: When the hamster Nibbles has rolled back to Skinner, it takes the lid of the ball off, and the lid lands on the ground. When the hamster is rolling away from Skinner it doesn't put the lid back on, it just leaves it on the ground, but in the next shot the lid is suddenly gone.
Continuity mistake: When the children are sleeping in the canteen at school, Bart is resting his head on a red sweater. In the close up of him and Lisa, the sweater has now turned dark green. It's not because of the dark that we see it like that because there is a bit of light at the beginning of the next shot and we see the jumper to be dark green.
Continuity mistake: When the Hamster rolls through the glass of Flanders car it breaks it near the bottom middle of The Front windshield. Later on when Flanders and Homer are taking the kids home you can see the break in the glass has now moved to about halfway up The Front windshield. On of the following shots it moves back to its original position and then moves back to being around the middle of the windshield.
Continuity mistake: When Homer sits down in the movie theater, all the rows are completely full, including the row behind him. When he turns around to talk to Selma, the seats directly behind him are empty. Then, when Homer turns back to the screen, the Sea Captain and Dr. Hibbert appear sitting directly behind him.