And Then There Were Fewer - S9-E1
Continuity mistake: When Muriel disappears after she's been accused, everybody rushes back up the secret passageway stairs to find her, and in the first shot facing the group there's a large green desk pad on the desk, but in the next shot that desk pad has vanished (and it reappears when they split into groups). (00:21:55)
And Then There Were Fewer - S9-E1
Continuity mistake: When Joe concludes that Stephanie was in the wrong place at the wrong time, the dining room table is still set with plates, wine glasses, etc, but then Joe tells everyone to look around for more clues, and in the next overhead shot as they all exit the dining room the table is bare. (00:15:55)
And Then There Were Fewer - S9-E1
Continuity mistake: When Lois and Peter pack their suitcases and leave the room, as Lois walks down the hall she stops at Diane's open door. In this first shot from the hall there are double doors and a blank wall opposite Diane's open door, but in the next shot from inside Diane's room there's a painting hanging on the wall opposite her door. (00:39:55)
And Then There Were Fewer - S9-E1
Continuity mistake: When Peter and Lois are packing their suitcases, in the first shot Lois is removing things from the dresser's wide middle drawer, but as Peter and Lois walk out of their room that wide drawer has been replaced with two small drawers in the middle. (00:39:30)
And Then There Were Fewer - S9-E1
Continuity mistake: In numerous shots we see the interior layout of the dining room, with the four sets of two story windows behind the arm chair at the head of the table. After Tom is accused of being the murderer, when he's captured in the dining room they're all behind the arm chair as they crack a joke about Adrien Brody. The problem occurs as the shot pulls backwards through the window, which is an average bay window instead of the four sets of two story windows. (00:37:35)
The Man with Two Brians - S7-E5
Other mistake: Brian puts in a video tape of him as a puppy. But he hasn't been with the Griffins since he was a puppy. Peter picked him up from the street as a homeless adult dog.
Continuity mistake: In the principal's office, when everyone's talking about how Chris sent an inappropriate picture, Joe is there. After Joe says "This makes Chris a sex offender", he's got a relatively pointed nose. In the wide shot his nose is rounded.
Continuity mistake: When the fat guys arrive at Peter's group, pay attention to the Asian guy in the first seat third row. After they open snacks he has switched seats with the other guy in the first seat second row. The guy he swapped seats with hair also changes color. (00:12:40)
The New Adventures of Old Tom - S14-E18
Continuity mistake: In the beginning of the episode the sign says "Every B deserves a J" underneath the sign of Jason's Jewelry but when Brian and Stewie go to return it that wording is gone.
Petergeist - S4-E26
Other mistake: The Griffins' house disappears when they flee, but when they go to Quagmire's house after, you can see their house when they are at the front door. Quagmire's house is on the right of theirs and the angle of the shot is to the left so it's definitely their house, not Quagmire's other neighbours on his right. (00:16:36)
There's Something About Paulie - S2-E16
Continuity mistake: A mob member at Cleveland's deli offers to help Peter get a new car by stealing the used junker he bought and have insurance get him a new one. The new blue car he receives appears to resemble a Volkswagen Beetle when it first appears, but in the second shot the car's body is more Mercedes-like. (00:05:17)
Road to the North Pole - S9-E7
Other mistake: Cleveland's house, across the street from the Griffins, is absent in the opening overhead shot. Then the scene changes to inside, and we can see his house through the window.
Continuity mistake: Peter, Quagmire, Cleveland and Joe are crawling through the air duct. Joes wheelchair is nowhere in sight yet when they fall to the floor it hits Joe in the head. (00:10:18)
Factual error: If one of a person's parents is an American citizen, that person has citizenship no matter where they are born. Since Thelma was a U.S. citizen, that makes Peter a citizen of the U.S. Also, were there no tax records for Peter since he had been married to Lois?
Other mistake: A bank wouldn't lock someone in the vault all night. Employees make sure customers have left before locking up for the day.
Death Lives - S3-E6
Other mistake: When Peter is dumped into the sea, a ship appears on the right hand side of the screen. However, the ship just appears randomly, it doesn't sail in to the shot, one frame its open water and the next frame it's there. (00:10:20)
The Former Life of Brian - S6-E12
Plot hole: Brian has a 13-year-old son. Not possible since Brian has only lived 7 years.
Other mistake: The guys all go water skiing, towing the boat behind Peter's car. After Quagmire gets his penis bitten off the scene cuts to the hospital parking lot. Quagmire's car is parked next to Peter's. There would be no reason to go home and get his car instead of going directly to the hospital. (00:07:15)
Plot hole: When Stewie and Brian are at the diner Stewie says he negotiated a deal with the mob by telling them he convinced Mort to give him his flash drive with the info to put the mobsters in prison. When they actually meet, Stewie tells the mob guys the flash drive is "his" and that he bought the coverage. Then he says his address is on the drive so they can mail it back to him. The mob guys didn't realise Stewie lied about whose flash drive it really was. (00:15:40 - 00:19:00)
Herpe, the Love Sore - S12-E16
Factual error: Stewie could not have gotten herpes by blood - it's only transmitted by infected saliva or skin.
Suggested correction: Please tell me that you are not a doctor! The two types of herpes viruses, HSV1 and HSV2 can be transmitted in blood as well as saliva. Such transmission is very rare as the virus deactivates rapidly in stored blood, but it is incorrect to say that it cannot happen.