Farhampton - S8-E1
Character mistake: When Barney is telling his story to Quinn in a minute he says, "Ted and I stopped being friends, Ted got hit by a bus, we made up." Barney got hit by a bus, Ted got hit by another car. (00:12:10)
Revealing mistake: When Lily brings out the "leaking" beanbag, you can see that she has the little white pellets in her clenched fist and is dropping them periodically, making it seem as if they're coming from the bag.
Factual error: The way Barney employs the green screen wouldn't work because a camera is needed to put a picture over the screen. To the naked eye the screen would still be green. The only plausible way to make the illusion work as intended would be a regular white screen and a projector, but this isn't the case here.
Continuity mistake: In 2-21 Something Borrowed, Lily's high school boyfriend, Scooter, reveals his name is Bill, but this episode in a flashback he tells Lily his name is Jeff. (00:03:47)
Continuity mistake: In 5-22 "Robots Vs Wrestlers" future Ted narrates, " No matter if we fell out of the group, we always made it to Robots Vs Wrestlers. Hell or high water." In this episode, Ted is the only one who goes.
Continuity mistake: We find out in this episode that Ted and the mother don't get married for several years, due to postponing The Wedding when she became pregnant. They eventually get married in 2020, when their children are 3 and 5. But in Lobster Crawl (8-9), at the end of the episode Lily and Marshal show up to babysit Ted's daughter when she's younger than that, and Ted is wearing a wedding ring. (00:29:00)
Suggested correction: Many couples wear rings before their actual wedding as a display of commitment. A friend of mine is in this situation. He wears a ring, has a child with his lady, but no actual date for their wedding is set. This is simply Ted choosing to wear a ring before getting married and there is no mistake.
Continuity mistake: After telling the joke about the Teenage Mutant Ninja Turtles, Marshall's hands change between shots, from holding his hand for a hi-five to his pockets to holding the Skittles. (00:08:32)
Factual error: When Ted recalls his trip to Spain the map onscreen is full of spelling and geographical errors: Marida appears in Portugal but it's in Spain and should be spelled Mérida. Valencenia = Valencia; Tarrogona = Tarragona; Grenada = Granada; Pamplona is placed where the city of Bilbao is; also Sevilla is placed 140 kilometers to the left of where it really is.
Continuity mistake: When Lily is talking about how much of a badass she used to be, it shows her meeting Scooter. He said his name was Jeff, but in season 9 Lily says that Scooter's real name is Bill. (00:03:40)
Band or DJ? - S8-E13
Revealing mistake: When Jason Segal (Marshall) gets blasted in the face with confetti, you can see him squint his eyes in preparation for it.
Other mistake: When Ralph Macchio mocks Barney for not gambling in AC, Barney makes a U-turn to head back, but turns the wheel to the right instead of the left. (00:12:00)
Other mistake: There is absolutely no reason for Ted to hang around underneath his apartment window while Jeanette is throwing stuff out of it. Any sane person would know that there is a very high chance of getting struck by the myriad of Ted's belongings that are wantonly chucked out onto the street. He's not trying to collect/catch anything because he is turned away from the building, and is not paying attention to the items that are being thrown out.
