This film's dedication is in "In tribute to the Allied pilots who took part in the Battle of Britain."
This movie was made about twenty-six years after the Frank Capra 'Why We Fight' documentary, The Battle of Britain, considered to have the same or similar title to this movie. The slight difference in wording of the titles is that the later picture drops the definite article (i.e. the "the") in its title.
Towards the end of the film, a British Spitfire flyer shoots down a German bomber, which then falls over central London before crashing into a railway station. This actually happened, (although the fighter used in the real incident was a Hurricane, not a Spitfire and the bomber was a Dornier Do17 rather than a Heinkel 111). The RAF pilot didn't shoot the bomber down, though; he had run out of ammo when he spotted the bomber apparently trying to attack Buckingham Palace. In desperation, he rammed the bomber, taking off the tailplane. The fuselage then crashed into Victoria Station. Incredibly, he managed to parachute to safety. His own plane rammed into the ground at 350 mph. It was buried so deep that the authorities just left it there. In May 2004 the former RAF pilot was on hand as the remains of his aircraft were unearthed to make way for a new water main. Remarkably, part of the incident was captured on film, the tailplane fluttering down and the fuselage section (minus the wings outboard of the engines, which were torn off by aerodynamic forces) plummeting towards the ground.
When Air Marshal Göring asks what the two German officers needed to win the battle, the second officer says, "A squadron of Spitfires." That scene was based on Adolf Galland's request to Hermann Göring during the actual event.
When Air Vice Marshal Park first visits Squadron Leader Harvey, a double was used in place of Trevor Howard for the shot of him jumping out of the Hurricane because, as Guy Hamilton said, "You don't have elderly actors jumping out of elderly planes".
When the Germans are marching into Dunkirk they are accompanied by several vehicles. These are actually American: M2 Half Track Car fitted with a German MG34 machine gun, and a M37 105mm Howitzer Motor Carriage fitted with a heavy anti-tank gun instead of the regular howitzer.