The choice to place this series in Las Vegas was not random. Among U.S. crime labs, Las Vegas is the second most active, surpassed only by the F.B.I. lab in Quantico, Virginia. This fact is stated in the pilot.

Before it was acquired by CBS, the show was first offered to ABC in 1999, but the network rejected it as "too confusing for the average viewer."

All of the equipment in the lab is fully functional, and was purchased outright, donated, or loaned to the show for product placement.

Grissom and Catherine are loosely based on real-life LVMPD criminalists Daniel Holstein and Yolanda McClary, respectively.

While the majority of the techniques and technologies used in the show are accurate, and true to reality, the writers and crew readily admit that they "time cheat". Tests that take a few seconds on the show, often take several days or weeks in real-life.

Though not requested to do so by the producers, Marg Helgenberger attended actual autopsies over the course of the series for personal research purposes. The most "memorable" aspect of the experience was the stench, according to Helgenberger's account on BBC's Breakfast (November 3, 2011).

David Berman, who played Assistant Coroner David Phillips, is also a head researcher for the show.

The popularity of the show was credited for a large surge of applications for courses in forensic science.

A fallout between George Eads and one of the female writers of the show prompted the absence of Eads for five consecutive episodes in season fourteen, including the milestone three hundredth episode.

The original name of William Petersen's character was Gil Scheinbaum. He changed it to Gil Grissom because of his admiration for astronaut Gus Grissom.

The oft-mentioned Tangiers Casino that was built and owned by Sam Braun in the series is completely fictional. There is no such casino in Las Vegas or anywhere else in the world. The name is often used by television shows and movies to bypass any potential copyright issues, or if a local casino doesn't give permission to use their name or likeness.

A scene featuring Willows and Stokes making out was filmed for the first season, but was not aired.

William Petersen took a small leave of absence to perform on a Providence, Rhode Island stage during season seven, and the character of Michael Kepler (Liev Schreiber) was created to be a temporary replacement.

In July 2004, George Eads and Jorja Fox were fired (by direct order of CBS head Leslie Moonves) for breach of contract. CBS said that they were using delay tactics (refusing to show up for shooting) to force a pay raise at the beginning of the fifth season. They were soon rehired, but without a raise. They both denied that there was any contract dispute. Eads says he just overslept on the first day of production, and Fox said she didn't know about the letter of intent she reportedly failed to sign.

Real-life prosecutors have complained about something known as the "CSI Effect", where juries have unrealistic expectations about forensic science, either expecting copious amounts of forensic evidence, in even routine cases, or expecting an unrealistic level of accuracy and specificity from the tests presented.

Ted Danson's real-life daughter, Kate Danson, plays lawyer Jill McDermott.

Before Laurence Fishburne was named as William Petersen's replacement, John Malkovich and Kurt Russell were considered for the part. Malkovich really considered taking the part, but after talking to Petersen and Gary Sinise, personal friends, he didn't want to commit to a ten-month shoot.

Wallace Langham (David Hodges) and Liz Vassey (Wendy Simms) proposed to the writers the romance between their characters.

When asked about a possible CSI feature film, Creator Anthony E. Zuiker said he'd like to wait until after the thirtieth season to make it.

In real-life, the Las Vegas Metropolitan Police Department (LVMPD) Crime Scene Investigators (CSIs) are not detectives, and are called Crime Scene Analysts (CSAs). Most present day applicants are surprised to discover that the CSAs do not perform most of the tasks depicted on the series. For example, they do not interview suspects, they do not write or execute search warrants, and they do not make arrests. In real-life, they are directed around the scenes by the detectives and supervisors, not the other way around. Detectives are commissioned police officers (sworn personnel). CSAs are civilian personnel, not sworn, and do not have the same arrest powers as police officers. However, they are very skilled technicians, and are a component of the police response to crime.

D.B. Russell's (Ted Danson's) full first name is "Diebenkorn", which means "grain thieves" in German.

Under the glass top of Grissom's desk is a photo of the series' Executive Producer Jerry Bruckheimer.

The producers wanted to hire Katee Sackhoff to replace Jorja Fox when she left the show, but the executives at CBS and Jerry Bruckheimer Television overruled the decision.

This was the last CSI series to continue shooting entirely on 35mm film. The spin-offs switched to shooting digitally in 2009, in an attempt to cut costs. This series switched in 2013.

You often hear the characters referring to a four-nineteen, or sometimes a 4-45. These are the Las Vegas Metro 400 Event codes. The often-used 419 stands for "deceased person", while the less-used 445 is "explosive device threat".

Marg Helgenberger, George Eads, Jorja Fox, and Wallace Langham all appeared on ER (1994), but never in the same episodes.

The first crime scene investigator was Archimedes.

In response to a TV Guide interview that revealed Jorja Fox may leave this show, fans began a "Dollar for Sense" campaign, and sent over two thousand dollar bills to CBS. The campaign also included three banner flyovers of CBS in Los Angeles, and flowers for her every day for a week.

There were rumors of another CSI series that would be set in London and use "Eminence Front" as its theme song, but the show never materialized.

Sara has a tendency to become emotionally involved in any case that involves domestic abuse. This stems from her childhood in which her mother killed her father after suffering years of physical abuse. Similarly, Nick tends to become emotionally involved in cases that involve sexual abuse against children. This is due to him being regularly sexually abused by a babysitter as a child.

Jerry Bruckheimer produced William Petersen's feature debut Thief (1981).

The show utilizes a wide array of tactical flashlights. The most often-used light is the Surefire M4 Devastator.

Grissom and company use the Nikon F5 fitted with a multi-control back for photographing crime scene elements. As of the fifth season, this is no longer true. Most have different cameras. For example, Warrick uses either a Nikon D70 or Nikon D100.

In season fifteen, Jared Briscoe''s (Mark-Paul Gosselaar's) mugshot number is 4815162342, the same as the mysterious number sequence from the television series Lost (2004).

At the conclusion of each case, the culprits almost always confess their guilt to investigators, that would most assuredly not be the people interviewing them, this helps to wrap up the case in a Scooby Doo-like manner for the general viewing public.

Much like the other CSI series, many of the cases portrayed are based on real-life crimes. The writers make certain changes, such as names, location, and other details for obvious reasons, but some details, such as manner of death and how the crime was committed closely echo the real crime.

The TV channel Sky Living (UK and Ireland), in later re-runs, as is common with the other UK broadcasters of CSI: Miami and CSI:NY, generally edit certain scenes throughout the entire run to remove many of the visually graphic shots, and certain dialogue - most obvious during crime scene, autopsy, the crime "flashback" and theories, resulting in abrupt dialogue pacing changes, and changes in the music. Also, as with CSI: Miami and CSI:NY, entire episodes have been skipped from broadcast, likely due to the underlying episode story. This is partly due to different broadcast standards of graphic content in the UK, and to enable the series to be re-run in early morning, daytime and early evening timeslots, as the episodes still work with the light edits as investigations.

Gil Grissom, and later his replacement D.B. Russell, both have more than passing similarity to Sherlock Holmes. Like Holmes, Grissom is dispassionate with a fierce devotion to logic and little regard for societal norms of behavior; Grissom once smashed mustard jars in a grocery store to illustrate a theory, much as Holmes once practiced spearing a pig in a butchers to determine how strong a man would have to be to transfix a man with a harpoon. Grissom also possess a Moriarty-like nemesis, Paul Millander, whom he pursues in several episodes. Coincidentally, "Paul Millander" has the same initials as "Professor Moriarty." There's also a woman, Lady Heather Kessler, in whom he takes an unusual interest. Their relationship is similar to that of Irene Adler and Holmes. Both Irene and Lady Heather enchant Holmes and Grissom with their beauty, their wit and their resolution. Lady Heather often wears Victorian-style dresses, referencing Holmes's era. Whilst D.B Russell's official character sheet was described as "A west coast Sherlock Holmes who devours crime novels and looks at every crime scene as if it were a story waiting to be told". Both Grissom and Russell work with there CSI Partners Catherine Willows and Julie Finlay, respectively (both the equivalent of John Watson) whilst both working under the Las Vegas Police Department Homicide Captain Jim Brass (the equivalent of Inspector Lestrade). See also: Detective Robert Goren from Law & Order: Criminal Intent (2001). Adrian Monk from Monk (2002). Shawn Spencer from Psych (2006). Patrick Jane from The Mentalist (2008). All crime solvers based on the fictional character Sherlock Holmes.

Multiple guest stars on this show also appeared on Charmed (1998). Melinda Clarke (Charmed: Siren Song (2002)), Geoffrey Blake (Charmed: Apocalypse, Not (2000)), Nancy Everhard ([link=tt0539402, just to name a few. Numerous episodes feature at least two, sometimes three.

Laurence Fishburne (Raymond Langston) and Tracee Ellis Ross (Gloria Parkes) also worked together on Black-ish (2014) as Pops and Rainbow Johnson, respectively.

George Eads has the most appearances of all CSI members with a total of 335 episodes, but he didn't show up in the series finale TV-movie IMMORTALITY.

In the show, two singers have appeared linked to Selena Gomez: Taylor Swift (Selena's best friend) played Hayley Jones in CSI: Crime Scene Investigation: Turn, Turn, Turn (2009) (season nine, episode sixteen), and Justin Bieber (Selena's former boyfriend) played Jason McCann in CSI: Crime Scene Investigation: Shock Waves (2010) (season eleven, episode one), and CSI: Crime Scene Investigation: Targets of Obsession (2011) (season eleven, episode fifteen). Therefore, both die in the series.