Denzel Washington was cast in this film because of a trip to a doctor. He ran into director Tony Scott in the waiting room of a medical office and the two men started chatting. Scott had not seen Washington in person since they worked together on Crimson Tide (1995). Scott happened to see Dakota Fanning in I Am Sam (2001) the night before, and seeing Washington made Scott think using of them together.
The kidnappers first names in the movie, Daniel and his brother Aurelio, are the actual first names of real life Mexico City kidnappers in the late 90s, Daniel and Aurelio Arizmendi Lopez, the infamous "Ear Loppers".
Creasy's quote about arranging a meeting between the kidnappers and God is similar to a quote falsely attributed to General H. Norman Schwarzkopf. It is not clear whose work the original quote is, which goes: "It's God's responsibility to judge Osama bin Laden. It is our responsibility to arrange the meeting."
Dakota Fanning was missing her front teeth during filming. The film-makers debated whether they should add fake teeth on her and even made them for the actress. In the end, they decided not to use them.
In A.J. Quinnell's novel, Dakota Fanning's character in Italy, was named Pinta. After Tony Scott's changed the film's setting to Mexico, and discovered that "Pinta" is Mexican slang for "whore", he had the name changed to "Pita", and made her full name Lupita.
Tony Scott tried to have a version of the film made in 1983, but since the film would have been his second, after The Hunger (1983), Paul Davies, a journal article author, theorized that movie producers would have believed that Scott lacked the experience to direct the film.
Even though it was never actually mentioned in the film, John Creasy was a Force Recon Marine prior to working for the CIA. When Samuel Ramos (Marc Anthony) is reading through Creasy's "extensive" resumé in the car, it can be seen for a very brief moment that he was assigned to 2nd Force Reconnaissance Company, stationed at Marine Corps Base Camp Lejeune in North Carolina.
Writer Brian Helgeland was not really keen on writing a movie he probably would not end up directing, so the producers told him that Tony Scott was working on another project that he might shoot instead of Man on Fire. In the end, that other project didn't end up getting made, and Scott ended up directing.
When Creasy reads the address of Aurelio Sanchez on the piece of paper, you can see that the street name is 'Via Appia'. This street doesn't actually exist in New-Mexico, but it obviously refers to the ancient Via Appia road in Rome. Heavy criminals used to be crucified by the side of that road, to make a statement towards society and especially towards other criminals.
20th Century Fox wanted the film to be set in Italy. An early draft of the film script was set in Naples. Tony Scott argued that if the setting would be Italy, then the film would have to be a period piece, since by the 2000s, kidnappings became a rare occurrence in Italy. Mexico City became the setting of the film, because Mexico City had a high kidnapping rate, and due to other reasons. As a result, the character Rika Balletto was renamed Lisa Martin Ramos, and Pinta Balletto was renamed Lupita "Pita" Ramos. Ettore Balletto became Samuel Ramos.
Interesting name: John Creasey (with the second "e") was a popular and prolific British writer of crime and detective fiction, the original creator of The Baron (1966) and Commander George Gideon of Scotland Yard (filmed more than once, most notably with Jack Hawkins as Gideon in Gideon of Scotland Yard (1958).
Pita's dog is named Sam, ostensibly named after her father, Samuel, but also a reference to the original 1987 film. In that film, which is set in Italy, the girl who John Creasy is hired to protect is named Samantha "Sam" Balletto.
The trivia items below may give away important plot points.
In the original filmed ending, Creasy does not die in the car on the way to The Voice's house. The two meet and chat for a while about the price of human life. Creasy continually looks down at his watch. When the timer reaches zero, Creasy smiles. Then, the entire house explodes. This implies that Creasy used the rectal bomb that he used on Fuentes earlier in the film. Tony Scott cut the scene, because he felt that it did not fit in with the tone of the film.