When Sam hears Dean screaming his name, the audio is actually taken from the end scene of No Rest for the Wicked (2008) when Dean screams for Sam while in Hell.
Crowley's drink feature a miniature Devil's pitchfork.
When Bobby meets Metatron he says "This is the Scribe of God? He looks like a Fraggle." Metatron replies " I'm going to take that as compliment. That was an excellent program. " They are referring to the HBO children's program from the 80's Fraggle Rock, about small creatures called Fraggles that lived underground.
One of the contacts in Dean's phone is "Sandra D"
Fraser Corbett (Angelic Guard) previously had an uncredited appearance in the episode All Dogs Go to Heaven (2010).