Continuity mistake: When Barney and Ted are calling dibs on the girl at the bar, in the closeup her book cover clearly reads "Brideshead Revisited", but in the wide shot it's something else entirely, spread across several lines.
Subway Wars - S6-E4
Revealing mistake: When Ted uses his laptop to get directions to the restaurant, Bing shows Los Angeles (where it's filmed) as their current location, instead of NY where the show is set. (00:02:15)
Continuity mistake: There is a lot of foam in the glasses when Barney pours champagne, however after camera shot changes all the foam is gone. (00:10:15)
Continuity mistake: Randy's noise bleed moves from his left nostril to his right and then back again. (00:14:20 - 00:15:00)
Continuity mistake: When Randy reveals that he didn't sleep with Robin, the blood from his nose switches nostrils between shots.
Other mistake: When Marshall brings the large photo of The Captain into the apartment, he claims he took the photo the last time that The Captain picked up Zoey, but the background of the photo is not the inside of a vehicle.
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.
Suggested correction: Depending on the location settings on his laptop, they could be giving a false reading. My laptop shows I'm in Cardiff Wales while in fact I'm nowhere near.
Ssiscool ★
The show was actually filmed on a film set in Los Angeles which is probably why the laptop says Los Angeles as the current location. This most probably slipped past the editing crew.