Other mistake: The sphere operates through the opening and closing of Cavorite blinds to negate the force of gravity. It has no engines at all. Why then, when it lifts off from the moon, do you see a blast of what appears to be rocket exhaust?
Other mistake: Because there is no air on the moon, Cavor advises Bedford to touch helmets when they speak, otherwise they will not be able to hear each other. Yet there are several times where they seem able to communicate without doing so.
Suggested correction: Is this really a mistake? H G Wells wrote "The First Men In The Moon" over 1900-1901 before the invention of the aeroplane, when space travel was still a fantasy. By 1964 Yuri Gagarin and Valentina Tereshkova had flown into outer space, so the makers of this film knew what sort of equipment would be needed if you really wanted to make a trip to the moon. And this film shows astronauts in suits copied from those worn by actual astronauts. But the idea of the original book, and this 1964 film, was that a (very) eccentric English Victorian scientist led an expedition to the Moon. So, surely, if Victorian Englishmen and Englishwomen went to the Moon, they would have used the technology available at the time. Beside that, when they reach the Moon they find it is inhabited. Even in 1900 astronomers knew there was no life on the Moon. I don't think this film was meant to be taken too seriously, and that when they made the film they deliberately dressed the cast in deep sea diving suits as a joke.
Rob Halliday