Whilst waiting in the psychiatrist's office Sam is seen reading the July 2005 copy of Men's Health magazine. That issue features an interview with Jared Padalecki, the actor who plays Sam.
Jared Padalecki and Jensen Ackles had Tom Welling hiding in the backseat of the Impala during shooting of some of the scenes. Jensen Ackles and Tom Welling starred in Smallville (2001) together.
Riverview Hospital, a large mental health facility used as the main set in the season 1 episode Asylum, has also substituted for a prison, a regular hospital, and an apartment building on different episodes of the show. This is evidenced by seeing the same distinctive staircase in different episodes.
This is the first time that iron is established as a spirit deterrent.
This seems to be the first episode where Jared maintains throughout a deeper, firmer tone to his voice as opposed to the early Supernatural episodes and the Gilmore Girls (2000) days. The Season 5, Episode 9: The Real Ghostbusters (2009) parodies this where the Dean and Sam LARPers deepen their voices when they go into character.