The first appearance of the Greendale Community College flag.
The City College program is called City College Cosmic Pioneer and the picture of their simulator pod has the initials CCCP on the outside. CCCP is also the acronym for the USSR in its native Cyrillic alphabet, so it's likely they got their simulator from a Russian program. (More likely it was a reference to actual Soviet spacecraft, which were similarly marked.)
This episode references not only the space race during the Cold War between the US and the Soviet Union but also space related movies like Apollo 13, The Right Stuff, and Armageddon.
When Pierce is in the cage and says he's "feeling a lot better now" and that he's ready to be let out, this is a reference to Dr. Blair's similar lines in John Carpenter's The Thing (1982).
The motto on Greendale's flag, "E Pluribus Anus" (latin for "of many assholes"), is a mockery of the original motto "E pluribus unum" ("Out of many, one") which appears on the Great Seal of the United States.