When Sam and Dean are both in the hospital visiting Garth they exchange stories of what they have been up to. Dean informs Sam that Crowley 'helped' him and the two went to see Cain and Sam asks "You worked a case... with Crowley?" to which Dean replies "The devil you know" which could be a reference to the episode The Devil You Know (2010) (S5E20), in which Crowley 'helps' Dean locate Pestilence.
The scene when Garth wakes up could be a reference to the scene in Pulp Fiction (1994), when Mia Wallace wakes up because of an adrenaline shot.