- 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.
- Reinforcing the Casting Gag, the Fake Irish restaurant host Marvin who turns out to be her husband and co-conspirator in the crimes is played by Colin Cunningham, who played Pentagon liaison Major Davis on SG-1.
- During the episode "65 Million Years Off", Shawn can't remember the name of that movie with Sigourney Weaver where they dig all the holes, in which Dulé Hill (Gus) played Sam the Onion Man. Gus can't remember either.Shawn: This is just like that movie! You know, that movie with Sigourney Weaver? Where they dig all the holes?
- Another Holes reference occurs in "The Santabarbarian Candidate". When Shawn says that he needs a way to subtly derail his mayoral campaign, Gus responds with "I can fix that." (Except Sam the Onion Man meant that literally, not politically.)
- Also, heaven help us if the writers manage to cram in a West Wing reference.
- It finally happened! 7x10, "Santa Barbarian Candidate." The West Wing, his job as an aide, and his character's name.Gus: You know I could have made it to the White House, Shawn.Shawn: As an aide.Gus: You know it.Shawn: Say "Yes, Mr. President."Gus: Yes, Mr. President.Shawn: Sorry, Charlie.
- Also in 8x9 "Nightmare on State Street," there is a picture of Martin Sheen (President Bartlet on The West Wing) during Gus's dream sequence. Gus says "Papa?" to the picture.
- It finally happened! 7x10, "Santa Barbarian Candidate." The West Wing, his job as an aide, and his character's name.
- Shawn's mother, played by Cybill Shepherd, is named "Madeline."
- Shawn tells Gus to "not be the only black lead on a major cable network"—too late for that.
- 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.
- As Shawn, Gus and Juliet interview him, the music playing in the background is a remix of the film's theme.
- Danny Glover plays a baseball coach in "Dead Man's Curve Ball."
- In "Shawn Rescues Darth Vader," 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.
- "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 Wisenote .
- John Rhys-Davies plays the museum curator in the Indiana Jones-inspired episode.
- Autopsy Turvy: Henry dances with a woman who asks if she can call him Captain Magic. Corbin Bernsens (Henrys actor) character in Kiss Kiss Bang Bang exclaims Captain fucking Magic! just before he dies.
- 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 "No Country for Two Old Men," Parminder Nagra reminds Gus that she is much better at soccer than he is.
- 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 The 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.
- Season 8 has a Plot Arc involving Anthony Michael Hall as Santa Barbara's interim police chief, who is a skeptic. This is a send-up of Hall's starring role in the previous (also USA Network) series The Dead Zone, in which he plays Johnny Smith, an *actual* psychic (well, clairvoyant) who works closely with the police to solve crimes.
- 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 (suitable for TV) Catchphrase from the Lethal Weapon series.
- Christopher Lloyd's character going "Great Scott!" in "100 Clues."
- Shawn says that Gus needs cable to watch the season finale of Leverage in The Head, the Tail, the Whole Damn Episode. Jeri Ryan, who plays Tara in Leverage, guest stars in this episode as an oceanographer.
- During a dance sequence in the musical episode, Lassie briefly does some river dancing before Gus stops him. Timothy Omundson played a villainous, river-dancing leprechaun in the Disney channel original movie The Luck of the Irish.
- In the movie, Shawn and Gus find a manifesto on the villain's computer entitled "The Crimes of Juliet O'Hara." When Gus comments that it sounds like a title for a Hallmark movie (which Maggie Lawson has starred in a handful of) Shawn dismissively says that "Jules would never do a Hallmark movie."
- In Psych 2:
- Lassie's nurse, Dolores (played by Sarah Chalke), makes a reference to her scrubs, and gives Shawn and Gus this little line:"You know, I'm very familiar with the 'goofy white guy, tall sexy black guy' routine...
- Shawn asks Henry why he watches This Is Us when ABC has "the same show but newer." James Roday Rodriguez is one of the stars of that very same show.
- One of the items on Lassie's to-do list reads "tape Galavant."
- Lassie's nurse, Dolores (played by Sarah Chalke), makes a reference to her scrubs, and gives Shawn and Gus this little line:
- In "Not Even Close... Encounters" Lassie has a crap listnote where Tyne Daly, among others, is listed. Daly co-started with Lassie's actor, Timothy Omundson, in Judging Amy.
- In "Any Given Friday Night at 10PM, 9PM Central," Shawn is discussing the case with the football coach and he goes over a list of players with things they would like to keep secret. One of the names listed on the board behind the coach is Dorn. Corbin Bernsen played Roger Dorn in Major League film series.
Actor Allusion / Psych