Crowley calls Dean "squirrel." Crowley always calls Sam "moose." Squirrel and moose are references to the main characters from the 1960's TV cartoon The Bullwinkle Show (1959)
Crowley says, "Success has many fathers but failure is a Winchester." The actual quotation ends with "failure is an orphan" so Crowley is correct either way.
As Naomi is interrogating Metatron, he says, "Of the blessings set before you make your choice, and be content." He is quoting Samuel Johnson from "The History of Rasselas, Prince of Abissinia" (1759).
Crowley mentions the TV show "Band of Brothers" when being injected with human blood. Richard Speight Jr. (Archangel Gabriel) stars in seven episodes of Band of Brothers (2001) as Sergeant Warren H. Muck.