The storyline is loosely based on real life bank robbers Terry lee Connor and Joseph Daugherty. Many elements of their heists are accurately depicted in this film, including breaking into the home of a bank manager and giving a soda to one of their victims.
Val Kilmer was originally considered for the part of Joe, and Bruce Willis was originally going to play the part of Terry, but due to scheduling conflicts, Kilmer backed out, and Willis took over the part of Joe.
Hans Zimmer was the only choice for the music composing. However, Zimmer was just finishing Hannibal (2001) and Pearl Harbor (2001) at the time in London, and he already committed himself to Black Hawk Down (2001), which was recorded in the US. Barry Levinson said that he would move the film for a later release, waiting for the German composer, since they are good friends since Rain Man (1988). Zimmer politely refused it.
The trivia item below may give away important plot points.
At the cabin right after they "pick up" Kate, Joe stretches a drape between the two sides of the bed, saying he saw it in a movie once. Kate asks, "How does [the movie] end?" Joe says, "With a wedding." At the end of the movie Harvey marries Claire, the Pink Boots girl.