At age ninety-one, just a few months before his death, Fred Zinnemann, director of The Day of the Jackal (1973), on which this film is based, fought with Universal to change the title of the film. He said the original had stood the test of time and did not want the remake to have the same title.
In his first scenes, Richard Gere has a mustache and goatee, as he wanted to have a different look from his popular image. The studio, however, was unhappy, and so Gere and the director were forced to shoot an extra scene where Gere asks for a razor after accepting the job to explain his clean-shaven appearance in subsequent shots.
The large, remote-controlled machine gun is a mock-up of the Soviet-designed KPV (Krupnokaliberniy Pulemyot Vladimirova) Heavy Machine Gun. The weapon used for the mock-up is actually an American M2HB .50BMG Heavy Machine Gun with a lot of parts added to it to make it look like a KPV. The name "Polish ZSU-33" is fictional.
(At around one hour and nine minutes) When they're waiting for The Jackal to arrive by boat at the marina in Chicago, Mulqueen (Richard Gere) turns to Major Koslova and says, "Shall we dance?" Gere starred in the film Shall We Dance (2004).
The trivia items below may give away important plot points.
Bruce Willis asked for the scene where the Jackal kills a gay man to be re-shot, so it was obvious that he was being killed due to the fact that he knew too much (having seen The Jackal on a news report), rather than because he was gay.