The championship belt Barney holds up is a WWE World Heavyweight Championship belt WrestleMania IV-WrestleMania XIV
An extra feature of this episode is a sequence, called "How it DIDN'T happen", that shows Barney, Lily and Marshall starting to engage in their own threesome after Ted leaves his room.
Lily says "I'll say it right now, all sorority girls are sluts" in reality, Alyson Hannigan was a member of Alpha Chi Omega.
Busy Phillips, who plays Rachel in this episode, co-starred alongside Jason Segel (Marshall) in the short lived series Freaks & Geeks (1999-2000).
The title of the third episode from the third season is Third Wheel (2007) that refers to a threesome that Ted is about to have.