Actor Allusion: In Season 1, Episode 11 "He Loves Me, He Loves Me Not, He Loves Me, Oops He's Dead" Shawn and crew end up speed dating and Shawn's first date is played by Teryl Rothery, who played the character of Dr. Janet Fraiser on Stargate SG-1. In the episode she says that she was raised on a farm and had a pet goat named "Cassy." "Cassy" is the name of the alien girl she adopted on SG-1 as Dr. Fraiser.
The Bourne references in "One, Maybe Two Ways Out" get funnier when you realize that Franka Potente, the spy in the episode, played Marie in the Bourne movies.
Shawn's forensic pathologist source (played by Kurt Fuller) tells him that a victim was killed by a Winchester 70. Fuller played Zachariah, an angelic enemy of the Winchester brothers on Supernatural.
In "Yang 3 in 2D," serial killer Mr. Yin is revealed to be a professor of fine art and history. The actor who plays him? Peter Weller, professor of fine art and history at Syracuse University. He really IS Buckaroo Banzai!
Kristy Swanson is suspected of being a vampire in "This Episode Sucks." This is particularly ironic when you realize what role Swanson is famous for.
Lucien (Tom Lenk) in the same episode had a recurring role in The Series.
And they run into a bartender played by Corey Feldman from The Lost Boys.
In "Shawn Rescues Darth Vadar", Shawn tells an ambassador that he picked up his British accent from watching Phineas and Ferb's grandfather. The ambassador is played by Malcolm McDowell, who does the voice of Ferb's grandfather on Phineas and Ferb.
Really, it would be shorter to list the guest stars who don't get at least one of these jokes made about them.
Impossibly, Psych somehow inverts this in the finale with Val Kilmer, who is often referenced in the show, as the ever-offscreen Officer Dobson.
In season 6, episode 1, celebrity guest star Malcolm McDowell asks Shawn where he got his horrible British accents. Shawn responds, "I dunno, all the usual places I guess. Peter Pan. Geico Gecko. Phineas and Ferb's granddad." Phineas and Ferb's granddad is voiced by — wait for it! — Malcolm McDowell.
In "This Episode Sucks", Corey Feldman appears as the bartender in a Vampire Bar. As Shawn, Gus and Juliet interview him, the music playing in the background is a remix of the theme from The Lost Boys (The other two notable guest stars in the episode were Kristy Swanson and Tom Lenk, both famous for different incarnations of Buffy the Vampire Slayer).
"Dual Spires" is an homage to Twin Peaks, and guest stars several members of the original cast as citizens of the titular town. The guest stars are Sherilyn Fenn, Sheryl Lee, Dana Ashbrook, Robyn Lively, Lenny Van Dohlen, Catherine E. Coulson, and Ray Wise.note Wise is the only one not to play a citizen of Dual Spires. Instead, he reprises his role as a priest from a previous episode.
Ralph Macchio guest stars as the director of the police academy in "We'd Like to Thank the Academy." Shawn makes occasional references to his role as The Karate Kid; In one scene, he says "Yes, sensei," and later he says, "Well, don't just stand there and wax on about it."
In "One, Maybe Two Ways Out," Franka Potente guest stars as a secret agent on the run from her agency. This is a clear reference to her role in The Bourne Identity, and Shawn even makes reference to their adventure being like a Bourne film. This could also be a small reference to her earlier role in the film Run, Lola, Run.
In "Psych: The Musical," guest Barry Bostwick mistakenly calls an actress "Janet." When corrected, he remarks, "Dammit." This alludes to Bostwick's opening number in Rocky Horror Picture Show, which incidentally is also a musical.
Ally Sheedy, best known for her role as the therapy-addicted quirky "basket case" in The Breakfast Club, plays a quirky shut-in serial killer, who later is seen institutionalized.
In the season 7 finale, Anthony Michael Hall plays a consultant hired to whip the department into shape, and is then appointed Interim Chief after Chief Vick is suspended. Hall looking into the camera and saying "I don't believe in psychics" given his lead role as a psychic in The Dead Zone is pretty hilarious.
In "Cloudy... With A Chance of Murder," Shawn asks Henry whether he hangs out at the courthouse regularly. Henry replies that he usually only visits on Thursdays.
Season 6 episode 5; "Dead Man's Curveball", Danny Glover says "I'm too old for this crap", his Catch Phrase from the Lethal Weapon series.
Defictionalization: The bad news is, Fries Queso Dos Fritos most likely don't exist. The good news is, fans have created recipes to replicate them!
Directed by Cast Member: James Roday has directed and written a few episodes, as well collaborating with the creator on the general storyline. Season 8's "1967: A Psych Odyssey" was directed by Kirsten Nelson.
Genius Bonus: Some of Shawn and Gus's references can be quite obscure.
Not to mention how often the actors who play Shawn as a kid get switched (4 people now).
Lampshaded in "The Polarizing Express": Young Shawn tells Shawn he's the younger him, and Shawn replies, "You don't look like me." Young Shawn then comments that "we change all the time, sometimes from week to week."
What Could Have Been: During production of Season 6, Dule Hill said they might do a second Dual Spires episode, but it didn't happen.
Season 8 originally had eight episodes filmed and was in the process of writing five more scripts. Unfortunately, their budget was only enough to film two of those episodes to which they set up a poll to let fans decide which ones they would like to see the most.