The geeky guy that Robin tells Barney could be her soul mate is Martin Starr who played Bill Haverchuck in the 1999 Indie TV show Freaks and Geeks (1999).
Cobie Smulders and Martin Starr would go on to star in Spider-Man: Far From Home almost 15 years later. Though they wouldn't share the screen this time.
At the end of the episode the song "tubthumping" by Cumbawumba is playing. This also plays at the end of American Pie. Alyson Hannigan who plays Lily was in American Pie
Lily incorrectly refers to the swords used in the duel as a "broadsword". In actuality, the swords are sabers.