Many of the soldiers in the film are armed with M1A1 Thompson submachine guns noted by their triangular "bunny ear" sight housing including Pvt. Kelly (Clint Eastwood) and Master Sgt. "Big" Joe (Telly Savalas). These guns were specially requested by Kelly for his special squad to find the gold behind enemy lines, which is why they are not armed mainly with M1 Garand rifles like a normal squad. Throughout the film, the M1A1 Thompsons sometimes switch with older M1 Thompson submachine guns with more complex bolts and cheaper bolted peep sights on the back with no protective housings.
The older M1 Thompson submachine guns are seen in the hands of many soldiers, which had more complex bolts and cheaper style peep sights which have no protective housings like the M1A1s. They are mainly seen switching with the M1A1s throughout the film as a continuity error.
Pvt. Fisher (Dick Balduzzi) uses an M1 Carbine which he usually keeps fitted with a rifle grenade launcher fixed on the barrel as his main weapon throughout the film.
Despite the fact that the M1 Garand rifle was the most commonly employed weapon in the U.S. Army during WWII, the rifle is seldom seen and is never used or fired in the film.
The Belgian FN BAR Type D light machine gun takes the place of the American Browning BAR for the film with noticable differences such as a larger wooden forend, a removable barrel, cooling barrel fins, a pistol grip, and a dust cover which were added to the gun by the Belgian army for it to meet their military requirments. It is most notabley seen in the hands of Pvt. Petuko (Perry Lopez).
I'm having a little trouble with the FN BAR users names so I'm leaving them blank. Anyone feel free to help me out here.
Seen pintle-mounted on the U.S. Sherman tanks under Sgt. Oddball's (Donald Sutherland) command are Browning M1917 water-cooled machine guns, which one tank operator is seen firing at German infantry from inside the tank.
The anti-aircraft version of the Browning M2, the M3, is seen mounted on top of the Sherman tanks under Sgt. Oddball's (Donald Sutherland) command, noted by their perforated barrel shrouds. During the assault on the town, Pvt. Kelly (Clint Eastwood) mans the M3 mounted on Oddball's tank and fires it at a Tiger Tank before the Sherman destroys it with a shot to the weak rear end. The guns appear to be fitted with a muzzle blank adapter which dimensions are clearly smaller than a .50 caliber to allow enough pressure to cycle the gun, though the blanks being fired are indeed .50 BMG blanks.
