While the majority of the techniques and technologies used in the CSI shows 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.
In real-life, the Miami-Dade Police Department's crime scene processing unit is called the "Crime Scene Investigations Bureau (CSIB)", and unlike the television show, MDPD's CSIB technicians do not conduct laboratory testing. Miami-Dade Police Department has a separate Bureau that operates the Miami-Dade Crime Lab. Also, the CSIBs are not detectives, and most present day applicants are surprised to discover that the CSIBs 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). CSIBs 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.
Kim Delaney's exit from the show, early in the first season, was due to a lack of on-screen chemistry between her and David Caruso. The show runners used a so-called "trap-door" plot line, in which her character's letter to Horatio implied that she had returned to work too soon after having witnessed her husband's murder, and was still grieving the loss, therefore was unable to handle the rigors of the job anymore as head of the crime lab and was passing the torch to Horatio.
Season five, episode eight, "Darkroom", was personal for Eva LaRue (Natalia Boa Vista), because her sister Nika LaRue was photographed by serial killer William Richard Bradford. Nika LaRue was offered the role of Anya Boa Vista, but turned it down, due to the fact that it brought up very painful memories.
According to a March 2003 article in TV Guide Magazine, Producer Anthony Zuiker refused to cast David Caruso, because of his reputation for being difficult. However, after seeing Caruso's performance in Proof of Life (2000), CBS President Leslie Moonves convinced him to reconsider.
In every scene that includes a shot of a street, sidewalk, et cetera, the street, sidewalk, et cetera will be wet, giving an appearance that it just rained. It could be to set the mood, and imply the humidity of Florida (the over exposed exterior shots are to give the visual feel of the heat), common practice to ensure consistency between shots if a rain storm happens to pass through, a way to remove any trace of a reset scene (for example, wash fake blood away) or the director just likes the aesthetic.
In season eight, episode twenty, "Backfire", Wolfe and Walter are shifting through debris from the fire, looking for the point of origin. The victim's ghost enters the room, and Walter asks if anyone else felt a breeze. Wolfe quips "you've been watching too many Rob Zombie movies." This is a nod to the musician, who directed season eight, episode sixteen, "L.A."
Wes Ramsey, who plays Dave Benton from season seven, episode seventeen, "Divorce Party", had a previous role in season one, episode twenty-one, "Spring Break", like a sexual predator, who stalked girls to abuse them.
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.
Lieutenant Caine nicknames Ryan Wolfe as Mr. Wolfe, being the only one of the CSI with this kind of formal treatment. Phonetically, "Mr. Wolfe" sounds exactly as Harvey Keitel's character in Pulp Fiction (1994), who was named The Wolf or "Mr. Wolf".
The "Universal Channel" (UK and Ireland), for their early morning double bill showing in 2016, ran a slightly edited version of the series, to remove the more graphic visuals. Also, other revisions within each episode included some dialogue cut, or trimmed, and certain crime scene/autopsy table/computer screen visuals cropped and/or blurred. Entire episodes were also skipped over, most likely due to the relevant episode story themes and visual content unsuitable for broadcast at that time of day.