Steve McQueen did not socialize with the rest of cast because his character was anti-social and alienated himself from the rest of the squad.
Robert Pirosh was a Master Sergeant during World War II, serving with the 320th Regiment, 35th Division. He fought in the Battle of the Bulge, at Ardennes and in the Rhineland. He commanded a unit in Bastogne during the Battle of the Bulge was awarded a Bronze Star. Pirosh's war movies pay homage to the American front-line infantry of World War II. Along with this film, they are Battleground; Go for Broke!; Combat!.
Bob Newhart said in an interview that due to the film's ballooning budget, Paramount refused to provide more film stock to the set. The filmmakers ran out of film stock before filming the scripted ending. But the abrupt ending has helped the film gain a cult audience.
According to Bob Newhart's autobiography, 'I Shouldn't Even Be Doing This', Steve McQueen and Bobby Darin did not get along during filming. When stories of their feud appeared in the trade papers, the film's publicist was fired. But it was Nick Adams who leaked the story. According to Newhart, Adams felt so badly that he chased the publicist's departing plane yelling "I'm sorry!"
According to Bob Newhart's autobiography, 'I Shouldn't Even Be Doing This', his fee for night-club appearances increased during production and he really wanted to get back on the road. He would routinely go up to the director with ideas on how his character could be killed off. The director would respond, "You're in it to the end, soldier."
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. Bobby Darin reportedly overheard the comment and quickly replied, "Not while I'm around." (The full Mankiewicz quote: "Steve McQueens 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.'")
According to the 'Variety Movie Guide', "Recollections of an actual and tightly classified incident near the dragon's teeth of the Siegfried Line during the dark days of World War II inspired the story by Robert Pirosh, . . . creative activator of the film who bowed out as its producer along the way."
Althought you see Steve McQueen's character carry the M3, .45 ACP Cal., sub-machine gun know as the "Grease Gun", which the ammunition is feed by a long magazine, you don't see him carrying any ammunition pouches for this weapon and instead you see he's carrying only the shorter pouches on his ammunition belt for the M-1 Garand rifle. And those rifle ammunition pouches he's carrying are obviously empty, as they are all flat and appear to contain nothing.
Apparently, writer-producer-director Robert Pirosh left this film before it was completed after on-the-set problems with star actor, Steve McQueen. Pirosh is only credited as a writer (story and screenplay) and has no director or producer credit. After his departure, Pirosh contacted Selmur Productions about a television series about the American front-line infantry. This series would become Combat!.
Director Don Siegel did not want to shoot the scene where Bob Newhart's character has a fake telephone conversation with "headquarters" to fool the Germans listening through a microphone planted in the US bunker, believing that it had no place in the story. He was overruled by the studio, however. Newhart at the time was a hugely popular stand-up comic, and a major part of his act was having one-sided phone conversations. The studio ordered that the scene be shot in order to capitalize on Newhart's popularity. Newhart wrote his own lines for this scene.
During the production shooting of this movie, a number of actors including Steve McQueen and Fess Parker frequently arrived on set late and shot a number of scenes without rehearsal or little of it, without make-up. Apparently, these actors were working on other film projects at the same time in parallel to this one.
Screenwriter Robert Pirosh was originally set to direct the film but after repeated clashes with star Steve McQueen he was replaced with Don Siegel. Pirosh's script featured many blackly comedic scenes but most of them were not filmed, as Siegel wanted to make the film more dramatic. Disappointed, Bob Newhart tried to get Siegel to kill his character early, but Siegel refused.
Temperatures reached 117 °F during filming. Some of the day sequences were changed to night so the cast would not collapse from the heat.
The shoulder patch worn by most of the soldiers in the platoon is that of the 95th Infantry Division, a real-life military unit (nicknamed "Iron Men of Metz") that saw action in the European Theater during World War II. Today, the 95th Division is an Army Reserve unit headquartered at Fort Sill, Oklahoma.
The TV episode The Siege of AR-558 features a number of characters whose names are based on the names of actors and characters from this movie. They include Reese (Steve McQueen's character; Larkin (Harry Guardino's role), and Kellin (after this movie's actor Mike Kellin). The episode's story is also similar to this movie's.
The weapon Steve McQueen is using is an M3, .45 ACP Cal., sub-machine gun know as the "Grease Gun". It came into use late in the war replacing Thompson sub-machine guns. It was not a general issue weapon to infantryman, normally it was the crew weapon on a tank. Many "found" their way to the front line troops. This earlier model weapon had a charging lever on the side that you see McQueen using occasionally to clear the weapon as it jams. Later models (M3A1) were charged by simply pulling back on the bolt by inserting your finger into a recess in the bolt. The M3A1 wire stock included a tab to help load magazines, the ends threaded to accept a cleaning brush to clean the barrel and was used as a wrench to unscrew the barrel for disassembly. The weapon, only manufactured during WWII by General Motors Headlight division, at a cost about $20 vs. the Thompsons at a fee of $100 each.
This film's director Don Siegel once said: "I would never make a war picture unless it was strongly antiwar. No side wins a war. How hypocritical warring nations are. Both sides have their priests and ministers pray to the same God for victory. War is senseless and futile. It is true that hell is for heroes. It is equally true that for heroes there is only hell."
This movie's opening prologue is represented by segments of a speech by President John F. Kennedy.