The episode "In plain fright" was filmed on location in an amusement park named Playland in Vancouver.
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
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
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.