The point-of-view action sequences (where the audience sees everything from the perspective of one of the characters) required well over a year of preparation, planning, and careful rehearsal before they could be shot.
Director Kathryn Bigelow found that no existing camera system could accomplish the shots necessary for the point-of-view sequences, so Lightstorm Entertainment's research division spent a full year designing and fabricating a special camera for the production. Weighing only 8 pounds, the 35mm camera literally fit in the palm of the hand and featured interchangeable lenses, remote follow focus, and video assist (necessary since the camera had no viewfinder). The camera was then mounted on a SteadiCam-style portable rig, which gave the camera stability and mobility similar to the human eye.
The opening sequence of the film was shot at four separate locations, as one contiguous location could not be found. The cuts between shots were disguised by rapidly panning the camera around. Due to the pace of the scene, the sound men could not effectively record any of the actual sound on the set. All of the sound and dialogue in the sequence had to be overdubbed during post production.
In the scene where Lenny uses the S.Q.U.I.D. to watch a clip of his past with Faith, Faith throws a blue towel and him and says, "Dry me." It is a reference to Blade Runner where Zhora throws a towel at Deckard and says the same line.
James Cameron did extensive editing work, especially on the final action sequences, but he could not be credited because he was not in the editors union. He joined before making Titanic and is credited as an editor on that film.
In a scene between Mace (Angela Bassett) and Lenny (Ralph Fiennes), Mace says "...Right Here Right Now." This is exactly where 'Norman 'Fatboy Slim' Cook' obtained the sample from that is heard in his single "Right Here Right Now".
The single biggest challenge facing Matthew F. Leonetti and his crew, was discreetly lighting a seven-block stretch of Sunset Boulevard, so that both sides of the street could be filmed simultaneously with several different incidents going on.
When the character Mace (Angela Bassett) is delivering a speech to Lenny (Ralph Fiennes) about how memories are designed to fade, Lenny is crumpling in front of a poster of elephants - a well-known symbol of memory. Director Kathryn Bigelow was asked at a special screening if this was intentional, to which she replied, "No. I'm going to have to ask the art director about that..."
Early in the film, when Lenny's television is on, one of the predictions made for the new millennium is that Muammar Gadhafi will win a Nobel Peace Prize. Ironically, Gadhafi was captured and killed after the Libyan uprising in 2011, largely because he was viewed as a brutal tyrant and dictator.