Character mistake: Lois says to Quagmire, if you have any questions we'll be right across the street. They live next door obviously, not across the street.
Continuity mistake: Peter is sitting on the couch talking on the radio. You see the phone sitting on a table beside the couch. But when Peter picks up the phone to call Quagmire, the phone is right beside him, without him ever moving it from the table.
Factual error: You cannot get paternity test results back in one day. It takes 3 to 5 days or even weeks depending on the lab.
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