Charlize Theron appeared for free, as a "thank you" to John Herzfeld for giving her the breakthrough role in 2 jours à Los Angeles (1996).
The language spoken by Rose Hearn (Charlize Theron) is Afrikaans, one of the official languages of South Africa. She says, "Hello Mr. Botha, can I call you back? You would never believe who just walked in here, it's Eddie Flemming. Thank you, good-bye." Botha was a famous boxer in the 1990s from South Africa. Charlize was born in South Africa, and speaks fluent Afrikaans.
The scene in the bathroom, where Robert De Niro dunks his head in a sink full of ice, is a real trick that police detectives use to get over hangovers. De Niro discovered the trick during his research for the role, and was eventually written in.
The immigration officer at the beginning of the movie is a real immigration officer, not an actor.
Edward Burns gained twenty pounds of muscle to accurately play an arson investigator, as they have to have spent at least seven years in the fire service, and would gain muscle mass across their backs, chests, and arms.