Plot hole: Dr Marvin Monroe says to Marge he was gone for a long time because he was sick. That's impossible because he died in a previous episode and you can even see his tomb in the episode where Maud Flanders dies. [It could be argued that Monroe really was sick. It was never explained how he died and no one mentioned that he really was dead. The grave, the hospital named after him were in the simpsons universe with the belief he was dead. The clip show mentioned his death but alluded any specifics. As Marge mentions she thought he was dead and so could everyone else on the show.]
Add timeDr Wilson
Continuity mistake: When Homer writes an autograph for Ralph at the restaurant, Lisa is sitting opposite Marge, has yellow liquid in her glass and has red and brown food on her plate. In the next shot, Lisa is opposite Homer, has a blue drink and has white and green food.
Continuity mistake: When Homer goes to work, and Mr. Burns starts complaining about him, we can see that the two pictures are on the far side of the yellow machine on his desk. But then when the shot changes, they are on the other side of the yellow machine.
Continuity mistake: During the "performance" at the end of Marge's book, "Ned" is skewered by a harpoon and falls off the cliff. When "Homer" walks up to the cliff edge you can no longer see the rope trailing from the end of the harpoon. However, moments later he gets his leg caught up in it and is pulled over himself.
Add timeDavid Mercier