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.
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 seconds in the show often take days or even weeks in real life.
According to a March 2003 article in TV Guide magazine, 'Anthony Zuiker' refused to cast 'David Caruso', because of the actor's reputation for being difficult. However, after seeing Caruso's performance in the movie Proof of Life (2000), CBS president Leslie Moonves convinced him to reconsider.
In real life the Miami-Dade Police Department's crime scene processing unit is called the "Crime Scene Investigations Bureau (CSIB)", but unlike the TV 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 CSIB's are not detectives and most present day applicants are surprised to discover that the CSIB's so not perform most of the tasks depicted on the series. E.g. 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). CSIB's 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.
In every scene that includes a shot of street, sidewalk, etc - the street, sidewalk, etc 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 (ie wash fake blood away) or the director just likes the aesthetic.
Wes Ramsey, who plays Dave Benton from "Divorce Party" (season 7, chapter 17) ahead, had a previous role in "Spring Break" (season 1, chapter 21) like a sexual predator who stalked girls to abuse them.
S8e20 Backfire: Wolfe and Walter as 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 musician who directed s8e16 titled LA.
Season 5 episode 8 "Darkroom"was personal for Eva LaRue who plays Natalia Boa Vista because her sister Nika LaRue was photographed be 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.
Lt. 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 as The Wolf or "Mr. Wolf".
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.