[1] Moore, a Harvard classmate of Robert F. Kennedy, wanted to write about the United States Army Special Forces.

One Special Forces officer in the opening chapter is "Captain Steve (Sven) Kornie", who was based on the Finnish expatriate Larry Thorne.

[2] The chapter depicted a fierce battle in real life when Special Forces Detachment A-734, stationed in the Tịnh Biên District, was attacked; all members of the detachment were later awarded the Purple Heart for injuries sustained in the fighting.

Production included extensive cooperation from the U.S. Army, which insisted that Moore not be involved with the film.

To please the Pentagon, Wayne bought Moore out for $35,000 and 5% of undefined profits of the film.