Martha Smith, who played Babs in National Lampoon's Animal House (1978), has a brief cameo as a bus tour guide at Universal Studios. This is a reference to the ending of Animal House, where Babs was said to have become a tour guide at Universal Studios. It's also referenced after the credits of several movies at the time in an advertisement for the studio tour ("Ask for Babs").
Joel McHale portrays Chevy Chase in this project. The two costarred in Community (2009). A number of episodes centered on McHale's character fearing he would become like Chase's one day. When McHale called Chase and told him that he would be playing him in the film, Chase gave his blessing and shared with him stories about Doug Kenney.
O'Donoghue says "I don't write for felt" in reference to the Muppet sketches on Saturday Night Live (1975). This is a real quote from Michael O'Donoghue concerning his dislike toward the sketches.
When Doug and PJ are researching old high school yearbooks Doug spots one picture where the name is "Lawrence 'Larry' Kroger" which is the real name of 'Pinto' in National Lampoon's Animal House (1978).