When Jeff is talking about Neil still being around doing this and that in the background, Neil is actually seen standing with the extras in the background behind Jeff.
The name of Hank's (David Cross) character in the game, "Tristram Steelheart," is a reference to "Community" executive producer and director Tristram Shapeero.
At the 11:10 mark, Chang (Ken Jeong) offers Hank Hickey (David Cross) a fist-bump. Hank rolls his eyes and taps Chang's fist three times: the exact same gesture his estranged father, Buzz Hickey (Jonathan Banks), makes to others on the show, e.g. to Britta (Gillian Jacobs) in 5:5 Geothermal Escapism (2014).
Hank refers to Abed as "Aziz." This is a reference to comedian/actor Aziz Ansari, who is Indian American. He also happens to star in the NBC sitcom Parks and Recreation (2009) which followed "Community" on Thursday nights. Aziz Ansari and Danny Pudi have also joked about switching roles on their respective shows for an episode.