Shawn mentions Camp Tikihama multiple times this episode. This is a camp that Shawn and Gus went to as kids, and is most notable in Tuesday the 17th (2009), one of Psych's many episodes paying homage to legendary Horror/Thriller movies.
Shawn and Gus suspect a radio host named Redd Herring is the murderer, only to discover that he's just creepy and unnerving. A "red herring" is a term used in detective stories to label an intentionally misleading clue.
Corbin Bernsen, who plays Henry Spencer, also starred in the B-horror film Dead Air (2009) as Dr. F.
At one point on Gus' radio show Shawn yells "make a wish" in a similar voice to how Gus yells "make a wish" in the season three episode Disco Didn't Die. It Was Murdered! (2008).
The radio station call letters are KJAD, which is actually a radio station in Topeka, KS.