* ActorAllusion: Christian Slater previously played a JD in ''{{Film/Heathers}}''.
* CaliforniaDoubling: Filmed in the Netherlands of all places.
* CreatorCameo: Renny Harlin as a mannequin in a phone booth later in the film.
* DeletedScene:
** One playing up Sarah's vulnerability much more - where she'd be seen behind a desk, after cracking under pressure during a field assignment.
** A scene in Harris's office where he chews out Sarah and JD for their bad performances. It helps foreshadow Sarah's possible motive to be the killer.
** At dawn a helicopter begins circling an FBI facility aggressively, before Gabe and Harris begin speaking. Also the students rappel out of the copter to get onto the island.
* DisabledCharacterDisabledActor: Averted with Vince. See below.
* DyeingForYourArt: LL Cool J dropped 40 pounds to star in this film. Val Kilmer is a strange case. He was to star in ''Wonderland'' next and required to have his hair long. He agreed to do this film if he could grow his hair for it. Cliffton Collins Jr spent ages in a wheelchair and working with a doctor to accurately portray someone with a disability.
* [[HeyItsThatGuy Hey It's That Guy]]: All over the place--
** [[Film/BatmanForever Batman]] is training profilers for the FBI.
** [[NamesTheSame J.D.]] is now trying to solve crimes [[Film/{{Heathers}} rather than committing them]]. [[spoiler:He dies first.]]
** [[Series/{{Dexter}} Jordan Chase]]/[[Literature/{{Trainspotting}} Sick Boy]] is [[spoiler:the killer.]]
** [[Film/{{Capote}} Perry Smith]] is still very fond of guns.
** [[Series/BandOfBrothers Private David Webster]] is once again one of the smart ones.
** [[Series/ColdCase Lily Rush]] actually [[spoiler:gets to live]].
** [[Film/VanHelsing The Wolfman]] is the sole Brit.
** [[Film/TheMummyTrilogy Ankh Su Namun]] is reincarnated yet again. [[spoiler: The God Anubis was (''again'') not smiling upon her.]]
* ManipulativeEditing: In the scene where Gabe describes each character - where Bobby is playing with the Rubik's Cube - Sarah was originally filmed sitting outside by the pool. Notice how close-ups are only used of Sarah in the scene - showing she was added in later.
* TheOtherMarty: Creator/GerardButler was going to play Lucas Harper, but dropped out to do ''Literature/{{Timeline}}''. Jonny Lee Miller was then cast in his place.
* WhatCouldHaveBeen:
** Creator/RyanPhillippe was also considered to play Lucas. Phillippe's then-wife Creator/ReeseWitherspoon was offered the role of Sara Moore, while Creator/ChristopherWalken, Creator/MartinSheen and Creator/GaryBusey passed on the part of Jake Harris.
** The film's original title was 'Unsub' - after a term used by FBI agents referring to an unknown subject (which is spoken a few times in the film). The studio wasn't happy with the title and changed it. The screenwriter was never happy with the change, given that there was already a book called ''Mind Hunter''.
** The water title sequence was filmed to be used as a flashback to Sarah's near-drowning experience. After production was over, it was re-edited to serve as the opening titles.
** Several different endings were filmed, including [[spoiler: Harris turning up alive and Gabe killing Lucas instead of Sarah]].
* WordOfGod: Rafe Perry, the coffee junkie, was an "English lend-out to the FBI" according to the director.
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