Corrected entry: When Brian and Stewie are in the universe without religion, Brian asks what happened to the art of the Renaissance and they go to the Sistine Chapel to see that John Hinkley decorated the ceiling. Why is there a Sistine Chapel in a world with no religion?
Corrected entry: When the family are at the school play, Brian suggests that it's possibly too soon for a musical about the tragic story of Terri Schaivo, implying that it's the first time the play has been done. However, Stewie (who is playing an electrical plug) meets Jared, who has been the plug every year for three years.
Corrected entry: At one point, Peter's father tells Lois "Maybe you won't go to Hell after all. Maybe you'll just be sent to Purgatory with all the unbaptized babies." Catholics believe that unbaptized babies are sent to Limbo, not Purgatory, and a fanatically devout Catholic like Mr. Griffin would know that.
Corrected entry: When Peter first has a piano in his bar, it's an upright model commonly seen in bars. The next night, it's a full sized Grand Piano. Given the width of the stairs, the size of the doorways, it seems unlikely to have been put down there without a considerable amount of effort.