Rufus and Flynn introduce themselves as Pinkerton detectives John McClane and Hans Gruber, characters from "Die Hard" (1988).
When Lucy introduces herself and Wyatt to Grace she says their names are Ally McBeal and Johnnie Cochran. Ally McBeal is a fictional lawyer played by Calista Flockhart and Johnnie Cochran famously defended O.J. Simpson for murder.
There were two papers mentioned when Lucy and her team entered in the hotel : (New York) Post and the (New York) Times. The Times has a more prestigious and affluent following while the Post, which was founded by Alexander Hamilton, has a more populist sentiment.
Throughout and especially at the end, Nicholas and Emma talk about a Rittenhouse agent named Andre whom they refer to as "him", and Emma claims that Flynn killed him. However, Andre is never seen, and the only Rittenhouse agent who is killed on screen is a woman. Andre exists entirely off-screen.