For the German aircraft, the producers obtained 32 CASA 2.111 twin-engined bombers, a Spanish-built version of the German Heinkel He 111H-16. They also located 27 Hispano Aviación HA-1112 M1L 'Buchon' single-engined fighters, a Spanish version of the German Messerschmitt Bf 109. The Buchons were altered to look more like correct Bf 109Es, adding mock machine guns and cannon, and redundant tailplane struts, and removing the rounded wingtips. The Spanish aircraft were powered by British Rolls-Royce Merlin engines, and thus almost all the aircraft used, British and German alike, were Merlin-powered. After the film, one HA-1112 was donated to the German "Luftwaffenmuseum der Bundeswehr", and converted to a Messerschmitt Bf 109 G-2 variant, depicting the insignias of German ace Gustav Rödel.