Deliberate mistake: When one of the yellow fire trucks moves away from the burning Thompson Tower, the back of the truck is set alight by the flames.
The Pieces of Fate Affair - S3-E23
Deliberate mistake: Because lawyers for real-life review columnist Judith Merrill were not amused by the parody of her and sued, the name Judith Merle is very obviously dubbed over throughout the episode (and changed in the credits) to Jody Moore. (00:32:50)