James Remar often went without any sleep before shooting his scenes in order to give bad-guy Ganz a more washed-out, psychotic look.
According to Eddie Murphy, he was almost fired for not being funny. He said he was not made aware of this until after the movie had wrapped.
According to Nolte in Nick Nolte: No Exit (2008), most of the dialogue between him and Eddie Murphy was improvised.
The first scene at the police station, which begins at around the twenty minute mark, was apparently shot in a single take. It lasts three minutes, with no visible cuts.
Walter Hill: [bar] One of a number of Walter Hill movies that feature a bar / night-club called "Torchy's".