Kirsten Nelson was pregnant in real life when she auditioned for her role as Interim Chief Karen Vick. During the first few episodes, she gave birth; from that time on she had to wear a fake pregnant stomach for the remainder of her character's pregnant period, to compensate for her diminishing belly.
A recurring gag featured in the show's outtakes involves the cast and crew laughing hysterically at the mention of the phrase "three-hole punch." According to James Roday, the gag began with a script written by Tim Meltreger, which included a joke about a three-hole punch. During filming, Roday misspoke the line as "three-hole puncher." Meltreger called for a cut and raced onto the set, then insisted that Roday read the line exactly as scripted, because, in his words, "Three-hole punch is *way* funnier than three-hole puncher!" Subsequently, it became a running joke on the set: someone says the words "three-hole punch" while shooting and the cast and crew all pretend to laugh as if it's the funniest thing they've ever heard.
Shawn and Gus almost always wear opposing shirt patterns (between plaid and striped). Shawn almost always wears short sleeves, while Gus rolls his sleeves to three-quarters. Even in episodes where they are wearing sweaters, the undershirts will alternate. In some episodes, Gus will wear a pinstriped suit while Shawn wears a plaid shirt.
According to his "MySpace" page, the following is a list of jobs that Shawn Spencer held before becoming the CEO of Psych: Newport Sailing Assoc., Newport Beach, CA US Assistant Race Chair 2006; English, Inc. Kho Samui, TH Teacher, TEFL 2005; Comerica Park Detroit, MI US Concessions Vendor 2005; Apollo Agency Seattle, WA US Foot and Ankle Model 2005; Ben and Jerry's Burlington , VT US Customer Service 2004; Minute Maid Park Houston, TX US Concessions Vendor 2004; Aquablanca Expeditions San Jose, CR Raft Guide 2003 - 2004; U.S. Cellular Field Chicago, IL US Concessions Vendor 2003; Flynn Special Events Santa Barbara, CA US Event Planner 2003; Mo's Outdoor Decor Santa Barbara, CA US Christmas Light Hanger 2002; Graceland By Night, Inc. Memphis, TN US Tour Guide 2002; Miller Park Milwaukee, WI US Concessions Vendor 2002; Oscar Meyer Wienermobile Madison, WI US Driver 2001 - 2002; Safeco Field Seattle, WA US Concessions Vendor 2001; Feedback, Inc. Santa Barbara, CA US Mystery Shopper 2000 - 2001; Turner Field Atlanta, GA US Concessions Vendor 2000; Assemblyman Skip Warner El Paso, TX US Constituent Relations 1999; Camp Durango Silverton, CO US Water Ski Instructor 1998 - 1999; Barrett's Mardi Gras Universe Algiers, LA US Construction 1997 - 1998; Hampton Inn Austin, TX US Desk Clerk 1995 - 1996; Pacific Emerald Cruise Lines San Pedro, CA US Lifeguard 1994 - 1995
Gus always uses Microsoft-related products while Shawn always uses Apple-related products. This includes their phones in later seasons where Gus can be seen using a Windows phone (e.g. s7e6 "Cirque Du Soul"), and it's well-known that Shawn uses an iPhone. Gus always uses a PC, and Shawn uses a Mac. Except for in some episodes where an Alienware laptop can be seen on Shawn's desk. This can clearly be seen in the episode "Forget Me Not".
The casting team for this show appears to have a marked love of 80's TV shows and movies. They've cast stars from TV shows Growing Pains, Family Ties, Family Matters, Cosby Show, Moonlighting, Married With Children, Good Times; and movies Breakfast Club*, Star Trek, Ferris Beuller's Day Off, Princess Bride, Pretty in Pink, Rocky Horror Picture Show, Ghostbusters, La Bamba, and Revenge of the Nerds. This is FAR from a complete list. 4 of the 5 students in Breakfast Club have appeared on Psych. The only one not cast is Emilio Estevez, although Shawn uses this name as a cover while investigating in the season 8 episode, "Someone's Got a Woody" (8.04).
A running gag in the show is that Gus and Shawn will frequently say "c'mon son!" when something strange, surprising, or silly has happened. This phrase was coined by media personality Ed Lover. In the season 8 episode "Remake A.K.A. Cloudy... With a Chance of Improvement", Ed Lover guest stars as a bailiff, telling Gus to "come on, son" as he attempts to escort him from the court room. He also appeared in season 6 episode "Last Night Gus" as himself.
Family Guy nods to this show in S8: E12, when Peter pretends to be psychic and helps the police force solve a crime. This is the whole basis of "Psych" and Peter even says he will psych out the criminal, which is a line in the "Psych" theme song
Several Psych cast and crew members have crossed paths before. Tim Matheson, Freddie Prinze, Jr., Carlos Jacott, Elden Hensen, Tamara Mello, Rachael Leigh Cook, and our own Dulè Hill appear together in the movie, "She's All That". Anna Paquin, Gabrielle Union, and Paul Walker are also mentioned, but don't make appearances.
In this show, the character Carlton Lassiter, played by Timothy Omundson, is named after 2 memorable characters from different 90's TV comedy series. The first one is Carlton Banks, played by Alfonso Ribeiro in "The Fresh Prince of Bel-Air". The second one is Paul Lassiter, played by Richard Kind in "Spin City".
The trivia items below may give away important plot points.
A running gag in the show are that Lassiter constantly metions a "Detective Dobson", but we never see him. Another running gag is that Shawn is told he looks like actor Val Kilmer. On the season finale, Detective Dobson is shown, and he is played none other than by Val Kilmer.
In the final episode, "The Break-Up", Chief Vick and Juilet mention that they can't hire Psych as a consulting team because they already have a guy and he is "alphabetizing the pantry as we speak". This is a reference to the television show Monk, which is set in San Fancisco.
4 out of the 5 Breakfast Club members. In the episode "Someone's Got a Woody", Shawn used the final Breakfast Club member (Emilio Estavez) as a nickname to get into a halfway house for an investigation.