Keeping in line with the running rock star gag Castiel introduces Sam and Dean to the local police as "Agents Spears and Aguilera".
In the bowling alley, Tyrus calls Metatron a "nerd". A reference to the actor's role in Revenge of the Nerds (1984).
The test that Sam and Cas pass in the warehouse hallway; "Only a penitent man shall pass" is from Indiana Jones and the Last Crusade (1989).
The name of the episode is also a song by Led Zeppelin from their fourth album.
Dean said to Sam "A hockey stick that can kill anything" in the bunker is likely a reference to the movie Dogma (1999) which also has the character Metatron.