Frederick Forsyth, who wrote the novel "The Day of the Jackal", insisted his name be taken off the credits of this film, which is why it is billed as "based on the screenplay".
Because Richard Gere and Bruce Willis filmed many of their scenes separately, they would often ask each other "How's your movie going?" when they'd meet.
After filming wrapped, Bruce Willis and Richard Gere reportedly vowed to never work with each other again.
This isn't the first time Richard Gere was considered for a role that Bruce Willis got. The first was the role of John McClane in Stirb langsam (1988), which Gere turned down.
In his first scenes, Richard Gere has a mustache and goatee, as he wanted to have a different look. The studio was unhappy, so Gere and the director shot an extra scene, in which Gere asks for a razor after accepting the job, to explain his clean-shaven appearance in subsequent shots.