Continuity mistake: When Brian is in the kitchen with the oven fire and an empty fire extinguisher, the side door behind Brian has its door handle on the right side, but when the family returns and Lois opens that door, the handle is on the left side of the door.
Continuity mistake: When Stewie is thrown from the swing and lands in another little girl's stroller, the inside is suddenly much larger after Stewie lands in it when the camera changes angles to how big it was when he was flying towards it. It suddenly has enough room for Stewie to be lying beside the girl with room to spare while she is still in the center, when it was barely big enough for her alone before he landed.
Other mistake: During the scene at the rehab clinic when Brian is jogging, Peter asks if he wants to go "mess with the pregnant teens across the lake." Brian says no because "Group therapy, two o'clock." However, the sky looks as if the sun is about to rise or just set. The time cannot be anywhere close to 2:00, neither AM nor PM.