The tank used in the film is an authentic Soviet T-55, captured by the IDF during the Arab-Israeli conflicts (although it was modified by the Israelis and re-designated as the Ti-67 and fitted with a 105mm main gun in place of the original 100mm gun). The film's military advisor, Dale Dye, said that he negotiated the purchase of the tanks over drinks with Israel Defense Forces officers in a Tel Aviv hotel.
For increased realism, 90mm blank shells were modified to fire a weight of water out of the tanks' 105mm cannons, thus causing the cannon to recoil as if it had fired a live shell.
Dale Dye, a retired US Marine Corps captain, served as the military/technical advisor and has an uncredited part as one of the helicopter crew.
Although in the original movie the actors use American military lingo and commands, which is quite out of place for Soviet soldiers, the Hungarian version of the movie corrected much of these errors and added authentic Warsaw Pact jargon and commands. Interestingly, the tank commander repeatedly calls a shrapnel shell "kartács" which is an outdated word for grapeshot.
George Dzundza campaigned hard for the role and went on a heavy diet and workout routine prior to filming, losing over 50 pounds in the process.