During one scene, Jensen Ackles (Dean) accidentally cut the face of the man playing a demon. The demon was portrayed by his stunt double.
Cain tells Dean that Abel wasn't the favored of God - rather, that Abel was being tempted by Lucifer. This mirrors Dean and Sam's relations to Heaven and Hell - only Dean was able to save his brother, where Cain killed his.
This episode features Timothy Omundson who predominantly plays a detective in Psych (2006), a show that often shared extras with Supernatural (2005) since they often filmed in the same areas.