According to Ben Mankiewicz of Turner Classic Movies, a columnist visiting the set commented on Steve McQueen's irascible temperament by noting that McQueen seemed to be his own worst enemy: "Steve McQueen's character in 'Hell Is for Heroes' seemed to have a little trouble getting along with people. By most accounts, playing that kind of guy wasn't a stretch for McQueen. Time and time again during production, McQueen got in the face of studio executives or Don Siegel, the director, or even cast members. At one point, a columnist was visiting the set, and he mentioned to another observer that Steve McQueen seemed to be his own worst enemy. Co-star Bobby Darin overheard the comment and quickly replied, 'Not while I'm around'."
Bob Newhart said in an interview that due to the film's ballooning budget, Paramount Studios refused to provide more film stock to the set. The production ran out of film stock before filming the scripted finale, but the abrupt ending has helped the film gain a cult audience.
Filmed mainly on soundstages, although the final battle scene was filmed on location in northern California.
Of the ten members of the squad, Bob Newhart was the only surviving actor at the 50th anniversary of the film's release, even though he was the oldest actor in the group (Fess Parker was older, but he was not part of the squad holding off the Germans). The two top-billed actors, Steve McQueen died when he was 50, and Bobby Darin, died when he was 37.
Temperatures reached 117° F during filming. Some of the day sequences were changed to night so the cast would not collapse from the heat.