How Lily Stole Christmas - S2-E11
Continuity mistake: When Ted, Robin and Barney are having a meal at the bar, we see Robin lift her drink to her mouth, then the shot changes to another angle and we see her lift the drink again.
How Lily Stole Christmas - S2-E11
Continuity mistake: When Ted, Robin and Barney are at the bar, discussing the fact that Barney is ill, the level of the drink in Robin's glass goes up and down between shots.
How Lily Stole Christmas - S2-E11
Continuity mistake: When Marshall and Ted are on the phone to one another, the string from Ted's hoodie changes position between shots, much of this may be because he is moving his hand due to being on the phone. However the right string goes back and forth from being caught on the collar of his jacket to hanging straight down over his jacket just before he is on the phone to his mother.
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