In the beginning of the episode, Dan and Vanessa are talking, where they mention (among other things), the city of Bucharest in Romania and the Vienna Opera. Sebastian Stan (Carter Baizen) was born in Romania and lived there until he was 8, when he moved to Vienna with his mother. He then moved to the US when he was 12 and eventually became an American citizen.
Chace Crawford (Nate Archibald) and Aaron Tveit (Trip van der Bilt) were both in the movie Undrafted (2016), playing Barone and Maz respectively.
Dan says to Nate after a family game, "This is Touch not Rugby". Penn Badgley, who plays Dan, also played Lars in Forever Strong (2008), in which he plays Rugby.