This film had to be bailed out by the production's insurance company after running over-budget and significantly beyond schedule.
The round Sigil Tattoo seen on Vin Diesel's neck is known as "The Gate of the Necronomicon" and is protective, symbolizing Man, the Creator and The Watchers.
At the time of the movie's release, director Mathieu Kassovitz openly opposed this movie, calling it a "bad episode of "24" (2001). In the interview with amctv.com , Mathieu Kassovitz said that Twentieth Century Fox interfered throughout this movie's production, which led him not to have a chance to shoot one scene the way it was written in the script or the way he wanted it to be.
The studio apparently cut 70 minutes of Mathieu Kassovitz's original version to get to a running time of 93 minutes. This happened against his wishes.
As a result of the feud between Mathieu Kassovitz and Fox studios over the final version, the movie almost didn't get any promotion at all.
Was not screened for US critics.
The film is based on a novel, Babylon Babies, by Maurice Georges Dantec.
In March 2007, the filming crew, having shot in the Czech Republic, took a two-week hiatus to deal with uncooperative weather, such as the lack of snow, and problems with set construction.
Vin Diesel dropped out of the lead role of Hitman (2007) just to star in this movie.
French actor Vincent Cassel was initially sought to be cast in the lead role
The Cyrillic tattoo on Vin Diesel's left hand reads "SLON" which stands for "Solovetsky Lager' Osobogo Naznacheniya" (Solovki Special Purpose Camp), one of the earliest GULAG's encampments (1923-1933). Later, this tattoo was popular among criminals, with a new interpretation: "Smert' Legavym Ot Nozha!" (Death for Cops From a Knife!).