A completely weird survior-of-nuclear-disaster film from 1959

Recent Criterion acquisition The World, the Flesh, and the Devil (1959), directed by Ranald MacDougall and starring Harry Belafonte has a few cool moments worth watching but overall it's so odd and out of date that it has to be chalked up as a curiosity piece deserving of its obscurity. In brief, an unexplained nuclear disaster wipes out (virtually) all human life on the planet; HB survives as he'd been trapped underground in a mine for the duration of the event. He emerges to find that he's - he thinks - the only survivor. He makes his way to an abandoned NYC where eventually he finds another survivor - a beautiful young woman (Inger Stevens) and, later, another male survivor. The two men face off in a sexual rivalry, leading to a shoot-em-out, manhunt and a somewhat odd conclusion, which I won't divulge. What's right w/ the movie and makes in at least a little worth watching are the fascinating scenes of HB in an abandoned NYC; I have no idea how they shot these scenes in 1959 - maybe via permits to film in the early morning, or maybe using streets marked for demolition (as they did for filming West Side Story), or maybe with sets and photograph backdrops? The other plus: the film directly deals w/ the issue of race (HB is black, the other 2 are white), leading to some provocative and disturbing arguments among the characters. On the down side, however, the film is completely absurd as a sci-fi fantasy, never even attempting to explain how or why NYC is completely abandoned: Where dia ll the bodies go? All the cars? All the animals (well, pigeons seem to have survived - no way to clear them out of a NY set I guess)? Moreover, the characters do not in any way behave as if they are the last survivors of a global disaster - virtually no mention of their past lives, no mourning nor distress nor fear - they're like 3 people on a camping expedition. In particular, the HB- Stevens scenes (before the arrival of the other man) are painfully ludicrous (MacDougall - screenwriter for The Breaking Point, which I recently watched, again shows himself to be a dialog-hack), and couldn't they have at least used HB's musical skills to better advantage? Over the years there have been many lone-survivors-of-disaster movies - I remember years ago seeing a Czech film that blew me away - but this one is one of the weaker, if one of the weirder as well.