Revealing mistake: When Robin storms into her room with her gun, she slams the door and the entire wall shakes. (00:20:00)
Factual error: When Ted is having a flashback about the first road trip in the Fiero, which would have happened around 1997or 1998, they are passed by a 2002 GMC Sierra. (00:06:10)
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.
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 Ted is on top of The Lighthouse (with both girls), his and the girl's hair is blowing in the wind, but the trees behind them aren't moving at all.