Untitled Griffin Family History - S4-E27
Character mistake: When the family is about to drown in the panic room and start arguing with Peter about not liking "The Godfather," Chris starts listing off the great actors in it. "Robert DeNiro, Al Pacino, I mean, you've never seen...ROBERT DUVALL!" Robert DeNiro is in "The Godfather Part II," but not in the first one. (00:19:30)
The Courtship of Stewie's Father - S4-E16
Character mistake: Lois takes a basket of clothes downstairs to wash them. But she puts them in the dryer instead of the washer.
Answer: Mort is Jewish, and Walt Disney was said to be antisemitic. So it would make sense in a Disney universe all the inhabitants would share his supposed beliefs.
MasterOfAll