Most of the playful banter between Derek Morgan (Shemar Moore) and Penelope Garcia (Kirsten Vangsness) stemmed from the way the actor and actress talked to each other in real life.

When David Rossi (Joe Mantegna) joined the team, he made a comment that their offices are better than "that bunker" out of which the B.A.U. used to work. The comment isn't metaphorical. The actual B.A.U. (in its many earlier incarnations and titles) used to operate out of a bunker former F.B.I. Director J. Edgar Hoover had built below F.B.I. Headquarters in Quantico, Virginia.

The character "Penelope Garcia" was supposed to be in only one episode, but she tested so positively that she was added to the main cast, and has the highest appearance count appearing in all but one episode (Season 13 Episode 20; "All You Can Eat").

Matthew Gray Gubler does not wear matching socks, because he thinks it's unlucky. In a few of the episodes, you can see his mismatched socks.

The entire cast have mentioned that they are like one big family. Joe Mantegna calls Shemar Moore and Matthew Gray Gubler his "golden boys".

J.J.'s children are played by A.J. Cook's actual children, Mekhai Andersen and Phoenix Anderson. Thomas Gibson's son Travis Gibson appeared in an episode that he directed. Joe Mantegna's daughter Gia Mantegna made a few guest appearances.

David Rossi has mentioned he knows Sir Ringo Starr. There is even a picture of him and Starr on Rossi's desk. Joe Mantegna and Sir Ringo Starr are friends in real life.

When Matthew Gray Gubler initially auditioned for the show, he was told that he was not right for the part. However, he was called back to audition again a few more times and was consistently told that he wasn't right for the part. After several more auditions, Gubler was eventually given the role.

As of season thirteen, Matthew Gray Gubler and Kirsten Vangsness are the only two cast members to have remained on the show since its inception, with other members having left the show (and return in some cases), or be fired. However, because Penelope Garcia was a recurring role during the first season, it is Matthew Gray Gubler (Dr. Spencer Reid) who holds the record as the longest-running main cast member of the series.

The character of Special Agent Reid was a child prodigy, having graduated from high school at age twelve. Matthew Gray Gubler, describing what may form his character's genius, has said that Reid may have Asperger's syndrome, and perhaps even be mildly schizophrenic. Reid's mother is schizophrenic.

In the show's opening credits, mug shots of real-life serial killers and mass murderers are shown. Amongst the killers shown are John Wayne Gacy, Charles Manson, Richard Ramirez ("The Night Stalker"), Ted Kaczynski ("The Unabomber"), Timothy McVeigh, Lee Harvey Oswald, and Susan Smith.

Before joining the B.A.U., Derek Morgan (Shemar Moore) was a highly decorated member of the Chicago Police Department's bomb squad, and is an expert at defusing explosives.

Kirsten Vangsness is the only main cast member to also be in the main cast of the short-lived spin-off, Criminal Minds: Suspect Behavior (2011).

During filming, Paget Brewster would often stash things in her boots, such as her phone, scripts, and cigarettes.

Jason Gideon and David Rossi were the two agents who formed the basis for the B.A.U. The characters, as young men, were featured in the story "Nelson's Sparrow". But the older characters were never featured together, and the actors who played them (Mandy Patinkin and Joe Mantegna) have never acted together.

Penelope Garcia was hired by the F.B.I. as a technical analyst after she was arrested for illegally hacking into their computer database. She was given the choice of working for the Bureau or being sent to federal prison.

Dr. Spencer Reid (Matthew Gray Gubler) has an I.Q. of 187, an eidetic memory, and can read up to 20,000 words per minute, as he stated in the first episode.

Lola Glaudini left the series during the second season because she was unhappy living in Los Angeles, and wanted to return to her native New York City.

Rossi's full name is David Stephen Rossi. Gideon named his son Stephen after Rossi.

The original title for the show was "Quantico", and the pilot was filmed in Vancouver, Canada. In the "Quantico" script, Jason Gideon was named Jason Donovan. Finally, a show named Quantico (2015) did come out, produced by the same company behind Criminal Minds, eOne.

Mandy Patinkin (Jason Gideon) has a son named Gideon.

In an episode when Reid (Matthew Gray Gubler) is looking into a case that could involve his father, he returns to his hotel room to find Rossi and Morgan watching a soap opera (The Young and the Restless (1973)). This is a reference to Shemar Moore (Morgan), who had a recurring role on the show.

As of 2019, Kirsten Vangsness holds the record for appearing in more episodes than anyone in the entire cast, having only missed one in season one. Matthew Gray Gubler comes in second, as he started taking time off in season eleven. The episodes where he was absent are "credit only".

At the beginning of filming season twelve, Thomas Gibson (Supervisory Special Agent Aaron Hotchner) was suspended from the show after a confrontation between him and a producer. After an internal investigation, and due to the fact that this was not his first altercation with a co-worker, he was terminated.

Kirsten Vangsness wasn't formally included in the main cast until the second season.

Spencer Reid and Penelope Garcia are godparents to J.J.'s son Henry.

Derek Morgan's son, Hank Spencer Morgan, was named for his father and Dr. Spencer Reid, Derek's "little brother".

Dr. Spencer Reid holds doctorate degrees in Mathematics, Chemistry, and Engineering, as well as Bachelor's Degrees in Psychology and Sociology. He is studying for a Bachelor's degree in Philosophy as well.

Reid is afraid of the dark because of the "inherent absence of light".

In the time between Mandy Patinkin's departure and Joe Mantegna's arrival (a span of only three episodes) Thomas Gibson received the "Starring" credit.

According to the site Looper, Shortly before the beginning of season 6, cast members Paget Brewster (Special Agent Emily Prentiss) and A.J. Cook were fired from the show. The official word from the network and production company came down to budget cuts, but according to Brewster, the real reason was far seedier. Reportedly, someone from CBS called Criminal Minds showrunner Edward Allen Bernero and ordered him to bring in "new women"--meaning younger women. Cook shot an episode to explain why her character, J.J., was going away, but Brewster's agent negotiated an additional 17 episodes before her demise. Actress Rachel Nichols was brought in to replace Brewster and Cook, and Brewster went on to shoot a pilot. Once the pilot wasn't picked up, Criminal Minds producers (new ones--Bernero quit) claimed that those 17 episodes constituted another year of her contract, forcing her to return to the show that had fired her (and killed off her character). After thousands of fans wrote in letters of complaint, Brewster and Cook, returned to Criminal Minds as well.

Elle Greenaway is fluent in Spanish. Emily Prentiss and Spencer Reid are fluent in multiple languages.

Throughout the series, we learn that Dr. Spencer Reid is from Las Vegas, Nevada. In reality, Matthew Gray Gubler was born in Las Vegas, Nevada.

This show was officially renewed for the fifteenth season on January 10th. The fifteenth season will be the final season. After the tenth episode of the fifteenth season, there will be three hundred twenty-five episodes, making it one of the longest running dramas ever.

Reid writes a letter to his mother every day so he doesn't feel so guilty about not visiting her.

In a 2012 interview, in New York Magazine, Mandy Patinkin said that he greatly regrets ever having accepted his role on the show: "The biggest public mistake I ever made was that I chose to do 'Criminal Minds' in the first place. I thought it was something very different. I never thought they were going to kill and rape all these women every night, every day, week after week, year after year. It was very destructive to my soul and my personality. After that, I didn't think I would get to work in television again. I'm not making a judgment on the taste (of people who watch crime procedurals). But I'm concerned about the effect it has. Audiences all over the world use this programming as their bedtime story. This isn't what you need to be dreaming about. A show like Homeland (2011) (on which Patinkin began appearing in 2011) is the antidote. It asks why there's a need for violence in the first place."

One of the signature images of this show is the brief shot of a business jet flying the team to a crime scene. Often these shots are paired as book-ends at the beginning and end of an episode, with voice-over of a cast member reciting a famous quotation. The jets shown are always Gulfstream products, including models G-IV, G-V, and G-450. Occasionally the shots are reversed left-to-right (for example, episodes "A Thin Line" and "I Love You, Tommy Brown"). The tail numbers shown are often registered to Gulfstream Corporation, indicating that the shots are taken from Gulfstream publicity materials.

In the time between Lola Glaudini's departure from the show, and Paget Brewster's arrival, footage was used in the opening credits that originally featured Glaudini. The footage, from season one, episode three, "Won't Get Fooled Again", was digitally altered, so that Glaudini did not appear.

Reid has memorized all of Rossi's books and biography.

Matthew Gray Gubler was once photographed by famed photographer Mia Grace, who had a small part in the series' pilot episode.

CBS aired an episode after Super Bowl XLI (2007) in the hopes of transforming the series from a relatively modest hit into a top ratings performer. The episode featured cameos by Super Bowl announcers Jim Nantz and Phil Simms.

Kate Callahan (Jennifer Love Hewitt) left the show after one season. She was replaced on the team by Dr. Tara Lewis (Aisha Tyler). Hewitt and Tyler played best friends and co-workers on Ghost Whisperer (2005).

Seasons fourteen and fifteen were shot together.

Both AJ Cook and Paget Brewster appeared on Law & Order: Special Victims Unit during their various hiatus from this show.

On this show, Keith Carradine played Frank Breitkopf, a serial killer that had been killing for thirty years. On Dexter (2006), he played Frank Lundy, who hunted a serial killer that had been killing for thirty years.

In season fourteen, episode four "Innocence," Alvez and J.J speak to an eager character at a crime scene who says "I've seen all the CSI's." Adam Rodriguez, who plays Luke Alvez, was a main character on CSI: Miami for many years.

Paget Brewster and Aisha Tyler appeared on the television show Friends (1994). Both played characters who were initially Joey's girlfriends, but shortly fell in love with Joey's friends and became their girlfriends. Paget's character was Kathy, who fell in love with Chandler and Aisha's character was Charlie, who fell in love with Ross.

Many fans have been asking when season thirteen will be available on streaming services. According to reports, it was supposed to release the summer of 2018 on Netflix, but never did. It hasn't been released anywhere and was removed from CBS All Access. As of March 2019, CBS hasn't announced when or if it will ever be added to streaming services or why there is a delay.

Mandy Patinkin's characters in this show and Dead Like Me (2003) have many similar interests. They were both shown to be capable and enthusiastic chefs, and have an affinity for art.

Thomas Gibson and Mandy Patinkin appeared on Chicago Hope (1994).

Derek Morgan is from Chicago, Illinois, and has Northwestern University football memorabilia on his office shelves.

On the show, suspects are routinely referred to as "unsubs", or unknown subjects.

It was the network's decision to cast Damon Gupton for the show. Producer Erica Messer had to create the character for him to play.

"C.A.R.D." is short for "Child Abduction Rapid Deployment" team.

J.J. collected butterflies as a child.

The only series in the "Criminal Minds" franchise without an Oscar nominee in the top-billed role. Forest Whitaker (Criminal Minds: Suspect Behavior (2011)) won Best Actor for The Last King of Scotland (2006), and Gary Sinise (Criminal Minds: Beyond Borders (2016)) earned a Best Actor in a Supporting Role nomination for Forrest Gump (1994).

M-VAC is a DNA collection system which vacuums up "touch DNA" from porous surfaces.

Matthew Gray Gubler's birthday is March 9th and Paget Brewster's is the day after on March 10th.

Jennifer Love Hewitt, Aisha Tyler, Jamie Kennedy, and Camryn Manheim appeared on Ghost Whisperer (2005).

Joel Murray, who played the Attorney General in season four, episode three,, "Minimal Loss", appeared with Thomas Gibson on Dharma & Greg (1997) as Greg's best friend and law partner.

The third Touchstone, later ABC Studios-produced show not to be aired on ABC. The other two ABC Studios-produced shows that have aired and/or still airing on CBS are: The Amazing Race (2001) and Ghost Whisperer (2005).

Erin Strauss is the most recurring character, appearing in 25 episodes over the duration of the show.

At one point, Poppy Montgomery was considered for the role for Ashley, but she was turned down to star in Unforgettable (2011) and Rachel Nichols was cast instead. Other actresses like Debra Messing and Leslie Bibb were also considered for Ashley before Nichols got cast

Though Joe Mantegna didn't join the cast until 2007, the series premiere aired about five months after the series finale of Joan of Arcadia (2003).

Matthew Gray Gubler was born and grew up in Las Vegas, Nevada like his character Dr Spencer Reid

At one point, before Edward Allen Bernero got the job as showrunner, Steven Bochco, who had a contract with Paramount at that time was considered. Bochco turned down the offer because he thinks it looked like the previous Bochco-created shows.

In the beginning of season five, Dr. Spencer Reid was shot in the leg. This injury was unplanned, but had to be written in because of Matthew Gray Gubler's real-life severe knee injury, which left him unable to walk for over four months. After a third surgery, Gubler started using a cane, but was unable to walk normally for the next five months. As of December 2009, he was once again able to walk unassisted.

Jason Gideon and Stephen Walker are the only main characters to have died in the series. Although, Gideon didn't die while he was on the show, he died eight years after his departure. Walker joined the team halfway through season twelve. His death was the first episode of season thirteen.

Spencer stopped drinking alcohol after Maeve's death. This might allude to his addiction and that he might have struggled to not start using again after her death.