It is believed that Gene Hackman wore his own Marine Corps billed cover (cap) in the film. Hackman is a Marine Corps veteran.
Chad Everett and Claude Akins also appeared together in Claudelle Inglish (1961), The Dakotas : The Chooser of the Slain (1963) and Medical Center : Time of Darkness (1973).
The basic story is very loosely based on the experiences of Sgt. John Basilone, the first Marine to win the Medal of Honor in WWII, although many liberties were taken with the true story at times.
James Best would gain mainstream success ten years later as Sheriff Roscoe P. Coltrane on The Dukes of Hazzard a decade later, but he'd been a working actor for a long time. Although in First To Fight, unlike a lot of other films and television shows, he does practically the same chortle/laugh (sounding like "koo koo") that would become iconic on The Dukes of Hazzard.
Made by Warner Brothers, the couple go on their first date to see a "new release" titled Casablanca, also by Warner; after which the Casablanca theme would become part of this film's soundtrack.