The central plot was adapted from The Beast From 20,000 Fathoms, though Godzilla's special effects are more basic: a man in a suit crushing miniature buildings. Conveniently, Godzilla is a nocturnal creature, with the darkness helping to camouflage some of the more crude effects. The night scenes are highly atmospheric, however, and add to the film's sombre tone. King Kong is another substantial influence, with Godzilla and Kong having equally tragic endings.
As in many other (primarily American) cryptozoological science-fiction films of the 1950s, Godzilla is a metaphor for the dangers of nuclear weapons, with the monster disturbed by atomic bomb tests in the Pacific Ocean. Godzilla is less sensationalist than its American equivalents, though, and is surprisingly bleak, with an explicit final warning: "if we continue conducting nuclear tests, it's possible that another Godzilla might appear somewhere in the world again".