Drawing from a well of pulp fiction, film noir and comic book imagery--not to mention influences from "The Wizard of Oz" to Fritz Lang's "Metropolis"--Conran and crew evoke a highly stylized 1939.
"Wizard of Oz" parallels are obvious, as are connections to Fritz Lang's "Metropolis" (no relation to Superman's hometown) and various others.
But black-and-white classics rich with light and shadow, such as Fritz Lang's "Metropolis" (1927) and Leni Riefenstahl's "Triumph of the Will" (1935), are also obviously major touchstones for Conran's sense of visual style, and there are also more recent influences such as the Indiana Jones series, the "Jurassic Park" series, and even "Who Framed Roger Rabbit?" (1988).
There are also plenty of film geeks who know and love the pulp fantasies of the early twentieth century, from Metropolis to the serialized swashbucklers of Buck Rogers and Flash Gordon.
Take a cultural grab-bag of such elements as art deco, RKO radio towers, sepia tones, dutch angles, expressionism, Max Fleischer cartoons, Superman and Flash Gordon serials, "Metropolis," zeppelins mooring to the Empire State Building, Manhattan of the '30s, P-40s with their Burma-battles Fei Hu nose art, and German secret-project scientists; add a dashing fighter pilot (Jude Law) shearling-sheathed in AAF garb and an equally mercenary and hard-boiled femme reporter (Gwyneth Paltrow) done in vintage Vogue duds—then attack the lot with huge airborne robots and batwing fighters letting loose with laser weaponry and you have "Sky Captain and the World of Tomorrow."
The result looks like nothing you've ever seen before, compiled very knowingly from many things you probably have: film noir, sci-fi pulp adventures from the '30s with garishly exhilarating covers, old Flash Gordon and Buck Rogers serials, and last, but not least, German Expressionist masterpieces like "Metropolis."