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 production ran out of film stock before filming the scripted finale, but the abrupt ending has helped the film gain a cult audience.
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'."
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.
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.
In his autobiography, "I Shouldn't Even Be Doing This", Bob Newhart said that he was offered increasingly large fees for nightclub appearances during production, much higher than the salary he was getting for this film. He really wanted to get back on the road, and would routinely go to director Don Siegel with ideas on how his character could be killed off. Siegel would respond, "You're in it to the end, soldier."
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."
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.
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. As it turned out, 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!"
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 is an Army Reserve unit headquartered at Fort Sill, Oklahoma.
During production a number of actors, including Steve McQueen and Fess Parker, frequently arrived on set late and shot a number of scenes with little or no rehearsal and without make-up. Apparently they were working on other film projects at the same time they were shooting this one.
Reportedly, writer / producer / director Robert Pirosh left the film before it was completed after on-set problems with Steve McQueen. Pirosh is only credited as a writer (story and screenplay) and has no director or producer credit. After his departure, Pirosh contacted producer Selig J. Seligman and his Selmur Productions regarding an idea he had for a television series about the American front-line infantry. This series would become Combat! (1962).
The weapon Steve McQueen is using is an M3, .45-cal. ACP submachine gun known as the "Grease Gun". It came into use late in the war, replacing the Thompson submachine guns (known as the Tommy Gun). It was not a general-issue weapon to infantrymen; normally it was the crew weapon on a tank. Many, however, "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 it was used as a wrench to unscrew the barrel for disassembly. The weapon was only manufactured during WWII by General Motors Headlight division, and cost about $20 apiece, as opposed to the Thompson submachine gun which cost abut $100 apiece.
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 and was awarded a Bronze Star. His other war films pay homage to the American front-line infantry of World War II--in addition to this film, they are Battleground (1949); Go for Broke! (1951) and the TV series Combat! (1962).
According to Don Siegel in his biography, he did not succeed in making Steve McQueen cry for a specific scene, even using the Stanislavsky method, until he put drops into McQueen's eyes to simulate the tears. Siegel said that McQueen had the strongest eyes in the world.
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".
Don Siegel says in his biography that the censors wanted to eliminate the words "damn" and "hell" from the script, because they considered them as outrageous. But Siegel insisted that they remain and they finally did.
Although you see Steve McQueen's character carry the M3, a .45-cal. submachine gun known as a "Grease Gun", which feeds ammunition via a long magazine, you don't see him carrying any ammunition pouches for it; instead, you see he's carrying only the shorter pouches on his ammunition belt for the M-1 Garand rifle. In addition, those rifle ammunition pouches he's carrying are obviously empty, as they are all flat and appear to contain nothing.
Many of the cast were angry over the studio's budget restrictions, which resulted in phony looking props, malfunctioning firearms and the same German having to be killed three or four times. In the last battle scene, Steve McQueen can be seen experiencing multiple failures firing the M3 Grease Gun. These malfunctions were due to problems with the blanks used.
Steve McQueen was reportedly furious with his agent for having induced him to sign onto the film and not securing the fee that he had been promised up front and for passing on another movie that he wanted. Thus, his angry, detached "loner" look may not have been entirely due to his method acting.