Continuity mistake: In the pilot episode, during the breakfast scene, there are five donuts in the box in front of Roger before his chair breaks. When he takes one from the box, there are eight. When Francine takes his donut away, there are five in the box again. (00:03:20 - 00:03:50)
Continuity mistake: Steve receives a Rowflux and five containers of protein powder. He takes one of the containers leaving only four still on the floor. In a subsequent scene, Steve is still holding the container but now five containers can be seen behind him, giving him six containers altogether.
Character mistake: At one point in the show, Roger throws a bucket of water (in disguise as Scotch Bingeington) on Francine claiming "Wet T-Shirt Contest!" Francine looks disgusted when Roger states "Eh, give this one a four" to the guy judging the contest, then says to Francine "Don't feel bad, you've had three kids." Francine replies "I've had two." and Roger gasps and puts a consoling hand on Francine's shoulder. This is wrong because Francine has birthed four children. She previously gave birth to Bailey (Hayley's twin), and Greg and Terry's baby in Season 3 Episode 7 "Surro-Gate." (00:14:15)
The 42-Year-Old Virgin - S3-E6
Continuity mistake: This episode reveals Stan has never killed anyone, even though he killed Jay Leno in Stan of Arabia: Part 1, killed Jackson's Double in It's Good To Be Queen, accidentally disintegrates one of his co-workers in I Can't Stan You, and shot a hang glider in An Apocalypse to Remember.
Cock of the Sleepwalk - S9-E11
Continuity mistake: After Stan says "Fired?!" and the camera goes back to Bullock, the word IHOP appears on the board behind them. (00:13:45)
Continuity mistake: Episode 1-10, "All About Steve": The boys are sitting at a table with a Star Trek poster on the wall. Stan walks in and the poster is gone. In a later shot it is back. (00:04:30)
Why Can't We Be Friends? - S8-E5
Factual error: When the guys are on the Graviton, you can tell they're spinning clockwise, or to their left. That means everything should be pushed in the opposite direction, but one girl's hair is flowing to her left when it should be flowing to her right.
Continuity mistake: When Francine goes to grasp the bottle of wine she was saving, the first one "told Klaus to shut up" has a cobweb on it. When she goes back to get it, there's no cobweb.
It's Good to Be the Queen - S1-E20
Continuity mistake: At the hotel, the dish with the strawberries is sitting alone on the round table. When Stan knocks it off, the table is now empty, but in the next shot, there's a phone and glass on the round table.
Other mistake: It appears as if Steve is holding 3 $20 bills when he supposedly received $50.
Criss-Cross Applesauce: The Ballad of Billy Jesusworth - S11-E17
Continuity mistake: When the game is tied 10-10, Yao Ming and Roger are in the circle at half-court, but when Ming checks the ball back, they are out and in front of the circle and not at half-court anymore. When Roger starts to dribble, he is back at the half-court line, all without them moving.
Continuity mistake: When Hayley closes the van door, Stan and the animals suddenly get a lot closer to the van. (00:08:40)
Continuity mistake: Stan's crocodile skin tie changes back to his ordinary black tie when he says "Prison rules" to himself.
Continuity mistake: When the avalanche happens the second time, all of the animals have snow on their backs. In the shot of all three of the animals, the snow has disappeared. (00:07:30)
Revealing mistake: While Hayley is throwing up into the bin, you can hear the sound of it going into the bin. However, you can see nothing is actually going into the bin while she is doing it.
The Kidney Stays in the Picture - S7-E16
Plot hole: It is explicitly stated in this episode that Hayley was conceived in 1996. While normal for shows without character aging to change birth years to benefit the plot, this move was premature. Hayley's permanent age is stated as 18, and this episode implies that in 2012 she would be much younger than this. The whole plot centres around her being legally able to drink in a bar, so this is a pretty big mistake.
Continuity mistake: The poop on the edges of Roger's robe that Stan wears disappears in later shots.
Revealing mistake: When Stan is at the launderette, a man is shown writing on paper. There is no ink shown on the paper. He's also only writing on one single line and not moving down after finishing the line. (00:01:10)
Roger Codger - S1-E6
Continuity mistake: When Francine is telling the kids heaven isn't real the brown chair normally seen isn't there. But in the close up shot of her, the top of the brown chair can be seen behind her. It's gone in the next shot though.
Chosen answer: The Beat.
MasterOfAll