Continuity mistake: At the start, the rug is next to Lois' feet. When Chris says about Meg's birthday, the rug isn't visible when it should be. (00:00:20)
Continuity mistake: Lois and Brian go outside and celebrate Peter's dad's death, then they come back in and sit down. Behind Lois you see the trash cans when Peter says, "But instead he called me a fat stinking drunk, those were his last words," then it cuts to a closer shot of Peter and Lois, and the trash cans have vanished. (00:12:33 - 00:12:54)
Audio problem: When Stewie knocks his glass off the table, it makes a shattering sound, but it doesn't shatter.
Continuity mistake: After Peter says goodbye to his family before his flight to Ireland, when it cuts to Stewie spying on Lois while she's doing the dishes, there's a calendar hanging on the wall beside the refrigerator and a paper hanging on the fridge, but when Stewie draws on the wall both the calendar and paper have vanished.
Continuity mistake: Peter goes to see his mom. She's drinking coffee and puts the cup down on the table to answer the door. In the next shot the cup disappears.
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