Continuity mistake: Just before Peter enters the tunnel in his new car, the white line in the middle of the road is blotchy and not continuous. When the shot changes to Peter's POV, the line has completely disappeared. The next shot which shows the car side on, there is now a straight white line on the road.
Continuity mistake: In the episode "The Cleveland-Loretta Quagmire" while the Griffin family are at the Heimlich maneuver class, there is a scene where Stewie is talking to a doll and putting his clothes on. You can see that he has no shoes on but when he sticks his feet through the pant leg holes, shoes suddenly come out of the pants and he has his shoes on.
Trivia: In the episode "Blue Harvest, part 1," Peter narrates a telling of Star Wars from his point of view. When Chris is walking through the bar, we see Bender from Futurama, Coach John McGuirk from "Home Movies," The Evil Monkey from Family Guy and The Alien from American Dad sitting in the background talking to people.
Continuity mistake: While Stewie and Olivia are performing, Olivia is wearing a light purple dress. After the performance, when Stewie and Olivia are sitting on the piano talking to their teacher, Olivia's dress changes from purple to blue in between shots. She is also wearing dark red lipstick instead of none at all.
Continuity mistake: In the scene where Stewie is eating chocolate cake, he shoves his head in it and covers himself in cake. However when Peter walks in after having liposuction, all the cake has disappeared and Stewie is now completely clean. The bowl of grapes on the table is also gone.
Continuity mistake: In the flashback when Peter fights Ernie the Giant Chicken, Peter gets knocked off the top of an eighteen wheeler and grabs the second rung at the bottom of the truck's ladder. But when the truck driver sees the pair in his side view mirror, Peter is hanging off the top of the ladder.
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: After Lois says, "When Meg and Chris turned one I missed everything," it flashes back to Lois writing 'happy birthday Meg' on the cake, and there's wallpaper border at the top of the walls, but when Peter asks her what she's doing in the kitchen the wallpaper border is gone. The paper cups that Lois filled with punch also vanish, and the rolling pin, board, etc. suddenly appear.
Continuity mistake: When everyone is in the dining room at the dinner table, the order of where everyone sits changes between shots. In all moments where it shows everyone sitting, the order is Priscilla, Derek, Jillian, Mort, Muriel, and Carl. But in one shot, the order is Priscilla, Derek, Jillian, Muriel, Mort, Carl.
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: In the episode where Brian and Lois get married, Lois confronts Brian after cheating with Peter back at the house. Stewie is playing with a SIMON SAYS game. Look at the SIMON SAYS when he is playing it (up close), after he is done (the close up shot ends), look at the colors again on the SIMON SAYS, they change.