To prepare him for filming, director John Herzfeld told Oleg Taktarov to watch On the Waterfront (1954), Spartacus (1960), East of Eden (1955), The Third Man (1949) and Moby Dick (1956).
Graham Knuttel, the Dublin-born artist, was paid £50,000 for a canvas which was destroyed in the film. The producers wanted the movie to be as realistic as possible, and so ordered the artwork to be destroyed in one scene.
At the beginning of the film, Robert Hawkins (Kelsey Grammer) is in a high-rise building (across from Times Square in NYC) talking to a woman sitting at a desk. They show him talking and the left side of his belt is on the outside of his coat. In the next shot his belt is back under his coat.
It refers to the Andy Warhol's suggestion that one day, everyone will be famous for 15 minutes of their lives. In this case, the two killers try and get famous through the media by claiming insanity.