Continuity mistake: When Stewie jumps off the side of the hot air balloon, he has no rope attached to his ankle. Next shot they show him hanging from the hot air balloon from a rope tied to his ankle.
Character mistake: In the cutaway gag involving George and Lorraine McFly from "Back To The Future" Lorraine says she hasn't seen Marty from high school since prom. George, Lorraine and Marty all attended the Enchantment Under the Sea dance in November 1955, not the prom, which is usually held in the spring.
Continuity mistake: At the Founding Father Restaurant, Stewie is drawing on a treasure map in red crayon and Peter takes it. In the next scene, where Peter shows the map to Quagmire and Joe at the Clam, the red crayon mark is no longer there.
Continuity mistake: In the episode "FOX-y Lady" (7-10) it was established that Quagmire was 61 years old. In this episode, Quagmire stated to Meg he was bullied in 1986 and a flashback shows that he was a teenager. So how could Quagmire have been bullied in 1986 as a teenager if he should have been in his 30's at this time? (00:12:15)
Factual error: Peter is posing as a blow up sex doll. The tester picks him up like he doesn't weigh anything. Not possible.
Continuity mistake: In episode 6, right before Brian's death when Stewie decides to go back inside the house to get his knee pads, he stops right before he enters the house. In this episode, when the same sequence is displayed along with Stewie (from the future) returning to that time, his former self never stops before entering the building. (00:18:40)
Continuity mistake: Peter's boss tells him to put on his helmet. He reaches behind him and out of nowhere, a red helmet appears in his hand.
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.
The Most Interesting Man in the World - S12-E17
Revealing mistake: When Peter is attempting to sneak into the Drunken Clam whilst keeping an eye on Stewie, Peter rips out his eye and throws it towards Stewie, though his glasses are in the way of his eye. (00:03:10)
The Most Interesting Man in the World - S12-E17
Continuity mistake: When Peter, Joe and Quagmire are watching Superman, they are first shown with three glasses on the table, one for each. After the scene of Superman is played on the TV, there are suddenly five glasses on the table. (00:03:30)
The Most Interesting Man in the World - S12-E17
Continuity mistake: At the Clam, when Peter mentions it was smart to wait out the thunderstorm, it is the middle of the day, but when Peter runs out of the Clam to go find Stewie, about 45 seconds later, it is suddenly sunset. (00:03:50 - 00:04:35)
Continuity mistake: When Joe, Peter, and Quagmire are sitting at the table in the bar, Joe takes off his sock and shoe to show them his foot. Cleveland comes in and Joe puts his leg back down and instantly has his sock and shoe back on.
