Trivia

Although neither Las Vegas nor Alabama figures in the plot, these two areas did play a special role in the film. Robert Duvall (Shrike), the mercenary hired by the plumbers to guide their rescue mission, to prepare for his part in the movie, visited Las Vegas to attend a convention held by Soldier of Fortune Magazine, the Bible of mercenaries, weekend soldiers, and weapon afficionados. There, Duvall had a chance to familiarize himself with the firearms and knives used by mercenaries, meet the men who have devoted their lives to fighting counterinsurgency and guerrilla wars, and pick their brains for ideas. Duvall also made a special trip to a mercenary camp in Alabama, where he had a chance to observe these professionals in action as they trained for future combat. One of the outcomes of these trips was a new look, including a shaven head, and a new catalogue of mannerisms, which Duvall brought to the film with stunningly realistic results.

Thomas F. Wilson and Gary Busey did not get along during the making of the film. Wilson references this in his Question Song by saying "Who is the nicest famous guy you know? Adam Sandler. Who is the biggest jerk? Gary Busey."

Tom Wilson appeared in this film and Psych (2006) season four, episode eight, "Let's Get Hairy", which is a reference to this movie's title.

Director Stuart Rosenberg didn't have his name on the movie, and was billed as "Alan Smithee", which is a pretend film industry name used by directors who don't want their names on a movie. "Variety" reported "Stuart Rosenberg took his name off the credits, reportedly due to a contretemps during post-production."

The surrounding area of Veracruz, Mexico included rivers and jungle which figured prominently in the story. The filmmakers added several features to the landscape. They built two jungle airstrips for the small planes used to transport the American would-be rescuers. The fields were constructed to appear as if they had been around for a long time. The company also constructed an elaborate jungle compound, headquarters for Carlos Ochobar (Guillermo Ríos), the renegade revolutionary who kidnapped Harry and the American ambassador to protect his lucrative contraband trade, and is willing to kill if necessary.