Plot hole: Brian bets Stewie about being at high school for a week. However, this was before Peter's stroke, and before the fire at McBurgertown. It would take at least a few weeks for McBurgertown was rebuilt, then Peter had his stroke, and then Lois tells Chris Peter's stroke was 3 months ago. After this scene, Stewie tells Brian he has lost the bet. However, the bet would only last one week.
Continuity mistake: When Muriel Goldman dies, everyone gathers up around her. When that happens, you can see Tom Tacker and Meg in the background, although they both disappeared a few scenes earlier. And than when everyone gathers downstairs, they do a body count and discover Tom and Meg are missing and only then are they found.
Continuity mistake: Just before the pest control team leaves for the Griffins', we see the black team member holding a shotgun in his hand. After showing Logan in shot, it returns to the black member and he's now holding what looks to be an MP5 machine gun. In the following shot as he starts to slide down the pole, the gun is once again a shotgun.
Continuity mistake: When Derek Wilcox is killed and on the ground, he is on his front with his head turned. He got hit above his right eye and blood is coming from underneath him, but after everyone else arrives outside, he is on his back with the wound above his left eye and blood is all over his face.
Continuity mistake: When we first see the sign outside the Quahog institute of performing arts, it has a cartoon take on the comedy and tragedy masks in the corners. In the left hand corner is a black mask with big ears and a smile and on the right is a white mask with a frown. Later on, the black mask has the frown and the white mask has the big ears and smile and the 3rd time you see the sign it has changed back again.