Continuity mistake: During Lisa's and Bart's segment, time seems to run really quickly. When Lisa leaves West Springfield Elementary it is 11:00 and when she gets to Moe's it is noon, then a few minutes later it is 2:50. When Bart and Milhouse find Fat Tony it is noon, then when Bart gets hit by the truck, it is almost 3:00.
Other mistake: On the DVD, When Homer is sitting on the Spinemelter, he says at one point "I've tried to fill it with family, religion, community service, but those were dead ends. This card is the answer". However the subtitles say "I've tried to fill it with family, religion, but those things were dead ends. This card is the answer", leaving "community service" out.
Continuity mistake: When Homer goes to Ned to make sure Marge imagines nothing again, Homer puts his hand through the door, then he puts his hand through the mailbox, then Nelson puts his hand out to steal the doormat. Nelson puts his hand just over the mailbox, then in the next shot when it reveals Nelson is there, his hand is suddenly under the mailbox without enough time to move it.