On the flashback sequence where Lily and Marshall switch scenarios with Barney and Robin, while they are " French kissing" vigorously, you can see Lily start to laugh and break character.
Edward Herrmann would pass away the 31st of December 2014, a few months later after this episode first aired and the series had already finished.
This is the third time they used the car sounds exactly the same once when the car went off on the sale for Lily's wedding dress. (Was an actual car sound) second when Ted had trouble with Zoey in his class and Lily told him to make the sounds of that car while turning the lights on and off to calm his students down. Then this time where Robin was talking about how her ex roommate sounds like a car during sex.
Cassie (Anna Camp) is introduced - along with her father, played by Joe O'Connor. Both actors appeared in Mad Men (2007) as Bethany Van Nuys, one of Don Draper's love interests, and Tom Vogel, father-in-law and business client of Pete Campbell, respectively.
More of a Goof When Lily is telling the reverend how she and Marshall met she mentions that she was drawn to his room but that it was random. A few episodes earlier she confessed to the group that she had seen him during move in and had tried multiple doors in the dorm until Marshall opened the door.