Character mistake: In another episode it is revealed that Robin hates nicknames and reacts badly when she, or anyone else, is given a nickname. However, in this episode her and Marshall give each other nicknames, and she doesn't seem bothered at all.
Other mistake: Robin says she burned the dinner because she mistook the temperature scale on the oven for Celsius. However a given temperature above -40 is always higher in Fahrenheit, so by assuming the oven to be labeled in Celsius she would have undercooked the food. For example: If the directions were to cook at 400°F, she would set it around 200°F (thinking the oven was Celsius.) If the instructions were to cook at 200°C, she would still set the oven to 200°F, undercooking the food in both cases.
Other mistake: When Marshall returns from Minnesota, he approaches Lily lying on the couch from the kitchen area rather than from the door, and Lily still acts surprised to see him, even when he was obviously already in the apartment with her.
Legendaddy - S6-E19
Other mistake: When Barney is trying to take down the basketball hoop, using the screwdriver, he never actually removes any of the screws.
Continuity mistake: When Ted leaves the bar he leaves his phone behind and yet he somehow still makes a phone call to Lily from the subway.
Revealing mistake: While showing the clip of Marshall streaking the first time, you can see thumbnails for videos of him streaking in New York. Those videos were created later that day and could not already be posted. One also shows a woman in yellow and appears to be a retake of the scene. (00:06:15)
Symphony of Illumination - S7-E12
Revealing mistake: While Marshall is on the roof putting up Christmas lights he accidentally drops his cell phone, which supposedly then falls to the ground where Scott picks it up and holds him hostage on the roof. But the cell phone can be seen to fall harmlessly into the gutter and can be seen behind the ladder, despite the added sound of it hitting the ground. (00:10:45)
Good Crazy - S7-E22
Continuity mistake: When Ted is on a date with the 2nd girl you can see her tattoos but when Ted sees Robin the tattoos change. (00:09:50)
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)
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)
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)
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.
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)
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.
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 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.
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)
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: 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.
