Continuity mistake: In the previous episode "The Wedding", Ted and Victoria first see each other whilst Ted and Barney are sitting together and both drinking champagne. In this episode, when the same glance is exchanged, a bridesmaid is sitting with Ted and Barney, and Ted is now drinking what appears to be whiskey. (00:01:00)
Continuity mistake: When Ted and Victoria are first talking, the straps on her dress keeping changing position between shots. Sometimes they are starting to slip off her shoulders, sometimes they sit straight, without her every adjusting the dress. (00:02:10)
Continuity mistake: When Lily and Robin are talking at the apartment, Lily's necklace keeps moving from on top of her jacket to hanging straight down over her dress.
Continuity mistake: The morning after The Wedding, when Lily is talking about throwing the bouquet, the mug in Marshall's hand changes position, vanishes and then reappears instantly between shots. (00:05:20)
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