Pierce says, "Ghosts can't go through doors! They're not fire." This is a direct reference to Chang's quote from The First Chang Dynasty (2012), where he said "Fire can't go through doors! They're not ghosts."
Abed makes a note that Pierce purchased his panic room on the same day as the theatrical release of Do the Right Thing (1989). Giancarlo Esposito, who plays Pierce's half-brother Gilbert and appears in this episode, was in the film.
In Pierce's bedroom, seen behind Jeff as he and Britta talk about Daddy issues is the painting of Chevy Chase that he had in his house in the first Caddyshack (1980) film.
Troy and Abed are dressed as Calvin and Hobbes, characters from a popular cartoon strip.
In Pierce's study, there is a Norwegian troll doll, much like the one he tried to give Troy in Remedial Chaos Theory (2011). There is a blank spot on the shelf where the doll from that episode likely used to be.