The episode "In plain fright" was filmed on location in an amusement park named Playland in Vancouver.
Shawn tells Gus "don't be the only black lead on a major cable network." Dule Hill was the only black lead on the USA Network at the time
Spot the Pineapple: a glass figurine (possibly the same one from Desperaux's hotel room) can be seen on Gus' desk. Also, the name tag reads "Piña", which is "pineapple" in Spanish
Ken says "Dude, I told you last time - 6 words" in reference to the amount of Chinese he speaks. Last time (S5E1, "Romeo and Juliet and Juliet) Ken said he spoke 9 words of Chinese, and six of those words are numbers.
A clown animatronic is spotted multiple times throughout this episode, known as Uncle Charlie, is a very popular Halloween decoration.