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)
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.
Plot hole: They're in the Clam complaining that they can't drink when they make the revelation that Brian can because he's technically 56. But Quagmire should be able to drink, as in a much earlier episode, he's revealed to be over 60.
Suggested correction: Quagmire considers the rest of them to be his best friends. He isn't drinking because they can't drink. He is complaining because since his friends can't drink - he won't drink, so he is still pissed.
It's still a plot hole considering Quagmire's age. I think the writers messed up big time.
You make a good point, but it's awkward to be that one person who is drinking while surrounded by people who can't. So, I understand the correction that was submitted above. Because his friends are not drinking, he now feels that he can't.
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.
The New Adventures of Old Tom - S14-E18
Continuity mistake: Peter goes to the roof where Tom is debating jumping. He has orange fingers because he ate a Doritos taco. He licks two fingers but next shot shows them all clean.
Continuity mistake: In the cutaway of Stewie talking with the three co-workers at the factory, there is a man towards the left of shot, leaning against a forklift. Beside the man is a female factory worker sitting on a crate about three to four feet to the left of him and her lunchbox is on the ground in front of the crate. In the next shot, as Stewie walks back to his forklift, the crate the woman is sitting on and the lunchbox are a much further distance from the man. The shot then pulls out, and the woman and her lunchbox are suddenly back to the original distance.
Continuity mistake: In the cutaway of Brian in the Old Yeller remake, he takes out a gun and goes to shoot a boy. When he first fires, the shell from the first gunshot lands on the ground beside him, but in the next shot, the shell has suddenly rotated itself by about 90° to the left.
How the Griffin Stole Christmas - S15-E9
Continuity mistake: Santa strangles Peter with his belt. He falls to the ground with a bruised neck. He turns around and the bruise is gone.
Continuity mistake: When Cleveland and Peter are in his car making sandwiches, Peter originally makes one sandwich that he splits with Cleveland. When the two men approach the car, saying they smelled something good, they offer $10 a piece for a sandwich. Peter then hands them each a sandwich that he couldn't have made that quickly.
Crimes and Meg's Demeanor - S16-E8
Continuity mistake: Peter and Meg are in a Greek week. There is a stair close to the front door while we see Peter's drinking. In the next shot, when Peter and Meg are leaving, the stairs disappear.
Crimes and Meg's Demeanor - S16-E8
Continuity mistake: At the beginning of this episode Peter is talking to Meg about her senior year in high school. This makes no sense considering she turned 18 in season 10, which was released in 2012.
Don't Be a Dickens at Christmas - S16-E9
Continuity mistake: Peter gets Lois a lawn chair. It vanishes from sight when Peter gives Meg her radio.
Other mistake: When Stewie and Brian are riding on the train, Stewie tells Brian, "It's nice that the locals act as their own train crossings." They are seated on the left side of the train and looking out their window at this time. As the train passes, we can see the only person standing there is on the right side of the train. Neither Stewie or Brian could have seen him from the direction they were looking. (00:14:10)
'Family Guy' Through the Years - S16-E16
Factual error: In the scene at the Disco, Peter and Quagmire both transpose "Viet Cong" but with "Donkey Kong." However, the segment is supposed to be taking place in 1973, meanwhile "Donkey Kong" wasn't released until 1981.
'Family Guy' Through the Years - S16-E16
Factual error: When the guys enter the disco in the 1973 segment, "A Fifth of Beethoven" by Walter Murphy is heard playing; that song was recorded and released in 1976.
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)
Factual error: While Trump is showing Peter around the White House, Trump stops and says, "Sorry, can you hang on a sec, gotta close this window, Melania's out there blowing bubbles for Eric." It's a fact that windows are not allowed to be opened in the White House for security sake. Michelle Obama was unaware at first and opened one and the secret service ordered her to shut that window immediately.
Continuity mistake: When Joe eats ice-cream on a mini batting helmet during the football match, some ice-cream is visible fallen on the ground just before the drink seller comes. In the next shot it disappears. (00:02:40 - 00:03:01)
Continuity mistake: When Meg, as X-Men's Quicksilver, starts to spite her whole family at the speed of light at the beginning of the episode - just after Chris sneezed in front of everybody - she initially throws his hat away from him, but in the next shot when she gets back on her seat, Chris' hat returns resting to his head.