Continuity mistake: Robin says that she doesn't like team sports, and so she only played tennis in high school. However, throughout the show, Robin often talks about playing hockey during school, which is a team sport.
Continuity mistake: At the bar, when Robin is telling the gang about Mike, Marshall's beer moves from in his hand to on the table between shots. Also, the amount of beer in the glass changes frequently depending on the camera angle.
Matchmaker - S1-E7
Continuity mistake: In the opening scene at the bar, when Ted and Barney are discussing the idea of going to visit a Matchmaker, Ted's beer glass suddenly goes from being about a quarter full, to being nearly three-quarters full. (00:02:20)
Matchmaker - S1-E7
Continuity mistake: At the Matchmaker's office, when Barney is saying he just wants someone to hold, Ellen is seen putting her pencil down on the desk but in the next shot it is in her hand again. (00:03:50)
Matchmaker - S1-E7
Continuity mistake: When Marshall comes out of his room with the book about the Roswell Incident, he's holding the cover and first pages bent under the book, next shot he's just holding them normally, then they're bent again. (00:14:30)
Matchmaker - S1-E7
Continuity mistake: In the final scene at the Matchmaker's office, the tub of Haagen Daaz on the desk turns around between shots. Sometimes the brand name is visible, but in other shots the logo is facing away from the camera. (00:20:00)
Continuity mistake: When Lily and Marshall are talking in the kitchen, we see Lily put down the recipe card to the left of the jar of mayonnaise. The shot changes and the card is now to the right of the jar. (00:06:25)
Continuity mistake: When Lily is making the layered salad, in some shots the layers are defined, but in others there is much more mayonnaise running between the layers. (00:07:30)
Continuity mistake: When Lily drops the potato chips on top of the 'salad', we can see a few chips sticking up beyond the top of the bowl. The shot changes and now the chips are laid flat, with none sticking up over the top. (00:07:40)
Continuity mistake: When Marshall and Lily are talking in the jail cell they are holding hands, then the shot changes and both have their hands in their laps. (00:17:35)
Continuity mistake: In the opening scene at the apartment, the mug that Ted is holding keeps changing positions in his lap between shots. Sometimes it is tucked behind the leg nearest the camera, whilst in other shots it is sat on top of that leg.
The Pineapple Incident - S1-E10
Continuity mistake: When Lily says "No dibs" and touches her nose, she does it with her right arm/hand, but in the next shot, her left arm/hand is on it. (00:05:55)
The Pineapple Incident - S1-E10
Continuity mistake: When Marshall gives Ted the phone to find out who's number is on his arm, he presses 2 buttons then gets through. No time to dial the number. (00:12:00)
The Pineapple Incident - S1-E10
Continuity mistake: When Trudy takes Ted's phone she grabs it with 2 hands. Camera cuts and now she has one hand on her face. (00:17:35)
The Pineapple Incident - S1-E10
Continuity mistake: When Ted is explaining to Robyn about Trudy he points at the door. Camera cuts and his arm has been lowered. (00:20:20)
The Wedding - S1-E12
Continuity mistake: In the first scene at the bar, as Ted heads off to speak to Robin, Marshall's beer goes from at his mouth to on the table instantly between shots. (00:02:15)
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