The opening scene where the vets in the hospital are talking was unscripted. They were real Vietnam vets discussing their own views about the war. Jon Voight was supposed to have added to the dialogue, but out of respect, stayed silent and listened.
Jane Fonda had wanted John Schlesinger to direct, but he declined as he felt that the Vietnam experience should be filmed by an American director.
Jon Voight's role of Luke Martin was loosely inspired by paralyzed Vietnam veteran Ron Kovic, who Jane Fonda had met at an antiwar rally and become friends with. Kovic was making inroads in Hollywood with his autobiographical book "Born on the Fourth of July" at the time, which was later adapted as Born on the Fourth of July (1989), with Tom Cruise in the role of Kovic.
Haskell Wexler: The director of photography appeared as the General during Captain Hyde's medal ceremony.
Hal Ashby: A passenger in a convertible sports car passing the one Jane Fonda is driving. He flashes the peace sign at her just as he passes.