Factual error: When Brian fires his pistol in the air, eventually killing the Super Devil, we hear six gunshots, each followed the distinct clink of the ejected cartridge hitting the ground. Trouble is, Brian is firing a revolver, which does not eject the cartridge after the bullet is fired. Only automatics do that.
Continuity mistake: At the Little Miss Texas pageant, just as Lois finishes saying "It's what you do when you're in Texas", she and Stewie walk past a judge and a little girl. In a close-up of Stewie, the judge and little girl have suddenly become a plant. (00:15:25)Casual Person