* Gil Grissom wasn't the character's original name, William Petersen dubbed him Grissom after astronaut Gus Grissom because he (Petersen) was a fan of the space program. Considering the original surname for the character was Scheinbaum, this was probably an upgrade.
* Gil Grissom's otosclerosis was supposed to be a more major storyline and a possible reason for him to retire. However, the show got a lot of letters about the fact that the condition is not that serious when corrected surgically. Hence, the surgery at the end of season 3.
* ActorAllusion: In a throwaway line A/V tech Archie mentions that he was going home to watch a variety of surfer movies. The list includes Local Boys, which is a film his actor starred in.
** Grissom informs Sara that he loves baseball when she tries to call him out on not liking sports. As any common male reared in the North Side of Chicago tends to be, Petersen is a life-long fan of the Chicago Cubs, usually stopping by Wrigley every season to sing "Take Me Out to the Ballgame", and narrated a documentary about the team.
** In 1x08 "Anonymous," Grissom turning to his reflection and "speaking to" the killer is reminiscent of a scene William Petersen had in {{Film/Manhunter}}.
* CastTheExpert: David Berman, who was a real life coroner before playing '[=SuperDave=]' Phillips, the coroner's assistant.
* {{Corpsing}}: Speaking of the surgery, Catherine's smirk is probably Marg Helgenberger's own; William Peterson wasn't wearing anything under his hospital gown during the scene. You can infer for yourself the view during Grissom's walking-away part of the scene.
** Helgenberger said in an interview once that the original idea was to have "THE END" superimposed over William Petersen's bottom as he walked away in the hospital gown, as a joke. [[ExecutiveMeddling Executives]] nixed the idea as they thought that was too corny and odd for a crime drama series.
* TheDanza:
** Archie Kao as lab tech/computer specialist Archie Johnson.
** David Berman as David Phillips, the assistant coroner (and baseball trivia expert).
** Larry Mitchell as Officer 'Mitch' Mitchell
* DisabledCharacterDisabledActor: Robert David Hall and Doc Robbins.
* HeyItsThatGuy:
** Creator/KimCoates plays a former porn star in a season four episode
** You may remember Archie as [[Series/PowerRangersLostGalaxy Kai the Blue Ranger]].
** Cordelia, Darla and Fred from the Buffy-Angelverse have all been on various episodes. So has Andy Umberger, who played more minor roles on both shows.
** Speaking of Buffy... [[Series/XenaWarriorPrincess Callisto]] cleaned up her act and is now a dentist by day -- and biting fetishist by night. Guess what her [[ScreenName SN]] is?
*** [[Theatre/LittleShopOfHorrors She has a talent for causing things pain. She'll be a dentist. People will PAY her to be inhumane]].
** [[Film/BackToTheFuture Jennifer Parker]] will succeed Cat Willows.
** Apparently, [[Series/{{Cheers}} Sam Malone]] and [[Series/{{Frasier}} Roz Doyle]] got married.
** [[Series/DueSouth Ray Vecchio]] is in Vegas now.
** [[{{CSI NY}} Danny Messer must have been undercover during season 3. And let's not even talk about what Adam was doing...]]
** GinaTorres from ''Series/{{Firefly}} is Warden Hutton.
** An early season one episode has David Kaufman as a murder suspect. [[WesternAnimation/DannyPhantom Maybe he was just fighting ghosts at the time]]?
** Scott Wilson, who played Sam Braun, is even more well-known nowadays as Hershel in ''Series/TheWalkingDead''.
** Both [[TheOffice Rainn Wilson and John Krasinski]] have appeared as one-off characters.
** A very young JennetteMcCurdy appears in an episode.
** Sierra and Mr. Dominic from {{Series/Dollhouse}} appear as minor characters.
** [[KateeSackhoff Starbuck]] has a recurring role as Detective Frankie Reed.
* HeyItsThatVoice: In the first few video games, many actors from TheOceanGroup play supporting roles. In most of the later games, Catherine Willows is actually [[{{Robotech}} Millia Fallyna]].
* IAmNotSpock: Petersen learned sign language for the episode it was in, but fans have tried speaking to him in sign not realizing he doesn't really know it.
* TheOtherDarrin: Ellie Brass, who was played by two different actresses in 'Ellie' and 'Hollywood Brass' plus 'Bang Bang'. Also Lindsey Willows, but hers is probably a bit more justified since she was a child and growing up fast and the earlier actresses may not have been available.
** Marg Helgenberger and Jorja Fox do not voice Catherine or Sara in most of the games.
* RealLifeRelative: Marg Helgenberger's now-ex-husband in two episodes (Weeping Willows and one more).
** Sort of with Gina Torres and Lawerence Fishburne, only Torres guest starred during season four, six seasons before her husband became the series lead.
* RealLifeWritesThePlot: Two of the original CSI series' episodes had to be rewritten to accommodate actor absences at the last minute. 'Gum Drops' originally had Grissom as the character believing Cassie was still alive, but William Petersen had to miss the episode due to a death in his family. So Nick was shifted into the lead. More recently, in 'Genetic Disorder', Greg had to be shifted into the lead role intended for Nick because George Eads was attending his father's funeral.
* YouLookFamiliar: Four of the franchise's primary actors (the ones in the opening credits) have appeared on all 3 series (there may have been more with the one time guest stars, a lot have done at least two) Lawrence Fishburne, David Caruso, Gary Sinise and Carmine Giovinazzo. But only characters Ray Langston, Mac Taylor and Horatio Caine have been on all 3 series since Carmine's guest appearance on the original CSI was 2 years before he began playing his ''{{CSI NY}}'' character. WordOfGod says the guest role didn't influence the CSI NY casting.
** Marlee Matlin appeared in a role each in CSI and CSI NY.
** A.J. Buckley, who plays Adam on CSI New York, appeared in one episode of the original CSI series beforehand. [[spoiler: He's the killer.]]
** Fans of both XenaWarriorPrincess and Firefly may recognize Lady Heather as a rogue Amazon and brothel madam, respectively.
* WhatCouldHaveBeen: A fourth CSI series was considered before {{CSI NY}} had ratings problems. It would have taken place in either New Orleans (another reason why the series never came to be, as Hurricane Katrina hit around that time) or London (which presumably would have set a new record for number of cast members being a FakeBrit).


!!This series has [[TropeNamers named the following tropes]]:

* TheCSIEffect
** Lampshaded in an episode where they become the subject of a ShowWithinAShow and mention that everything is edited together to make it look faster.
** Also lampshaded in a later episode when Hodges mentions that he's convinced everyone that most of the advanced equipment he operates takes twice as long to work as it actually does in order to get more free time.
* FingerprintingAir
** Note that on many occasions the characters complain about the lack of useful fingerprints, and sometimes the fingerprint collected doesn't match anything on the OmnischentDatabase.
** They subverted this in one episode - a cleanly lifted print in an old case is shown to be fabricated because there was no way that it could have been lifted from the surface claimed (an alligator-skin wallet).

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