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.
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.
Chosen answer: She was finally shown at the very end of the last episode of season 8, continuing into season 9. The actor's name is Cristin Milioti: http://www.imdb.com/name/nm2129662/.
Knever