While researching the novel in the early 1970s, author Frederick Forsyth pretended he was actually financing a coup d'etat in Equatorial Guinea. The pretense allowed Forsyth access to a number of underworld figures, including mercenaries and arms dealers. Forsyth has since commented that the arms dealers were the most frightening people he has ever met.
Tom Berenger has said in interviews that around half of his role was omitted from the final release print. When executive producer Norman Jewison asked him to go on a promotional trip to Japan, the angry actor vociferously refused. According to Berenger, Helen Shaver, who played his wife in the film, was totally eliminated from the release print.
The "dogs of war" phrase takes its literary origins from William Shakespeare. It appears in Act 3, Scene 1, line 273 of William Shakespeare (I)'s "Julius Caesar". It reads: "Cry 'Havoc!', and let slip the dogs of war". This Shakespeaean phrase was actually used as a tagline for this movie.