Other mistake: In the end credits where it says, "Special Guest Voice", Marcia Wallace's name is there. Mrs. Krabappel was originally supposed to be in the episode but wasn't because Jose Canseco disliked his original part. He was originally slated to wake up in bed with her and miss the game, but Canseco's then-wife, Esther Haddad, objected. (00:29:00)
Continuity mistake: When Lisa comes down the stairs prior to watching "When Buildings Collapse", the TV screen is near enough in the corner of the living room and can be seen from the stairs. When Lisa enters the living room, the TV has moved further into the room. Subsequent shots of the TV move it so far into the room that it would not have been possible to see it from the stairs at all in the first place.
Continuity mistake: When Grampa Simpson says "That's the activity room" to Mr Burns at the Retirement Home, you can see that Mr Burns and Grampa both have glasses on their trays. In the next shot, Mr Burns' glass is on the table and Grampa's glass has moved from the left to the right.