Jensen Ackles appears shirtless in this episode. This was devised by Eric Kripke to meet the overwhelming number of requests he was receiving from fans for Ackles to appear wearing less clothes.
In the first minutes of the show, we follow S.W.A.T. members into the house. The music playing is "In-A-Gadda-Da-Vida" by Iron Butterfly which pays homage to the 1986 movie, Manhunter (1986), where this exact scenario was first seen. "A Good Deal" by Mommy and Daddy has replaced "In-A-Gadda-Da-Vida" by Iron Butterfly for the streaming Netflix version.
The closed captioning for the episode reveals that "Poison Whiskey" by Lynyrd Skynyrd was supposed to feature during Sam's fight with the Dean/Shapeshifter, the lyrics even run in full in the captions though a regular dramatic piece of score music is heard instead.
Dean makes a Star Trek reference when talking about the shapeshifter's ability to absorb thoughts and memories, comparing it to a Vulcan Mind Meld. Episode director Robert Duncan McNeill is best known for playing the role of Lt. Tom Paris on Star Trek: Voyager (1995).
Jensen Ackles also played the brother of another Sam in Dark Angel (2000) with Jessica Alba. Also in Dark Angel he played 2 versions of himself Ben/Alec just like in season 1 of Supernatural with the shape shifter.