The film was noted for its generally realistic representation of the historical evacuation. It accurately depicts a few Royal Air Force aeroplanes dogfighting the Luftwaffe over the sea, limited to one hour of operation by their fuel capacity. The combat, however, is portrayed at much lower altitude than the reality. Destroyers and fighter aircraft were indeed held back from battle, as the Royal Navy and Air Force would have been the sole defenders against invasion. There was indeed a temporary withdrawal of destroyers during the early stages after considerable losses; however, an appeal to the Admiralty by Admiral Ramsay reversed that decision. Also noted were the accurate depictions of how a small boat evaded aerial attack, and of how soldiers returning to England saw a civilian population largely unaware of or unaffected by the war.[189][190] British officers did initially refuse to evacuate French soldiers, although Churchill later insisted that the French be evacuated alongside the British.[189] The realism of the film was acknowledged by Dunkirk veterans, although Branagh said that some thought it was "louder than the battle".[191]
Hispano Buchón masquerading as a Bf 109E, wearing a temporary paint scheme for the film[76]The characters and the storyline are fictional; Commander Bolton is a composite of several real men, including Commander James Campbell Clouston (the lack of an actual depiction of Clouston drew criticism following the film's release, and attention was drawn to honour him for his role in the evacuation)[192][193][194][195][196] and Captain Bill Tennant.[197] Dawson is inspired by Charles Lightoller, a survivor of the Titanic.[198][199][200] The character of Collins is analogous to the experiences of Spitfire pilot Jack Potter, with Collins's ditching partly inspired by that of Eric Barwell in his Defiant. Some media outlets suggested Farrier was inspired by Alan Deere.[201][202][203][204] When the beach scenes were shot, the weather was worse than during the real evacuation; Nolan explained that this helped to understand the danger faced by the pleasure boats.[205] In one scene, a non-commissioned officer gives a salute without wearing his military beret, which a veteran pointed out as inaccurate protocol.[78] Noses of German planes were not actually painted yellow until after the evacuation; this was done to differentiate the German planes. Contemporary shots were used for aerial views of the town, whereas Dunkirk was in ruins by the time of the evacuation. The design of the airborne leaflet propaganda was similar to those used in 1940, although the originals were not in colour.[189] The destroyer that is bombed and sunk represents HMS Keith.[206]
