Parodies the belief, popular when the show aired, that the ancient Mayan calendar predicted that the world would end in 2012, as well as the 2009 disaster movie (about people escaping this prophesied apocalypse on a spacecraft, with those eligible selected by ballot), titled "2012".
Richard Nixon refers to his assistant as the "Headless Clone of Agnew." In the Futurama movie, "Into the Wild Green Yonder," the original headless body of Agnew is killed, so his DNA was cloned at some point between then and now in order to reprise the character. (Note: Spiro Agnew was U.S. vice president from 1968 to 1972, under President Richard Nixon. In 1972, he resigned from office as part of a deal that allowed him to escape charges of extortion, tax fraud, bribery, and conspiracy allegedly committed during his many years in various elected offices. Nixon appointed House Minority Leader Gerald Ford to replace him, who incidentally became president after Nixon's resignation, and thus the only person to be an unelected vice-president and unelected president.)
Before leaving the doomed Earth, Professor Farnsworth says: "So long, Earth, and thanks for nothing". This is a reference to the "So long, and thanks for all the fish" message left by dolphins when they also evacuated the doomed Earth in the sequel of "Hitchhiker's Guide To Galaxy" book.
Fry says his "lucky" pants are also his only pants. However, when Bender jumps through the window to loot his own apartment, there's a pair of green pants draped over the back of the sofa. Bender doesn't regularly wear pants, so it's fair to assume that they belong to Fry, although they might have been "looted" by Bender from someone else.