This is the only one of Ray Harryhausen's films to be shot in anamorphic widescreen (2.35:1) due to the higher cost of anamorphic camera and projection lenses needed for his Dynamation Process.
In order to keep the audience's interest, and the flow of the film running smoothly, sound effects were added onto the moon scenes: their footsteps on the lunar surface, their rustling against rocks, clapping hands, and clanking helmets together, would all be totally silent since the moon has no air to conduct the sound.
Selenites were played by cockney street kids.
In the book, the large monster which the Selenites hunt is called a Mooncalf. This is an old English term for idiot, since it was believed that being out under a full moon could cause madness (think also "lunatic"), but is also a clever pun on H.G. Wells' part, as the Selenites also hunt this beast like cattle, the young of which is called a calf.
The Russian spoken by the astronauts at the film's beginning is in fact Czech.
Peter Finch: as the bailiff's man, around 0:43:43. He was reputedly only visiting the set when the original actor assigned to play the part failed to show up.