This was a great example of Honda's view or rather his hopes and dreams of what he hopes man could achieve. A long time pacifist, he saw a time that the world could come together and unite to achieve a common goal. This film highlights this more than most. The world council is comprised of countries that are often overlooked in Japanese films of the day, including China who were not the best of neighbors as far as Japan was concerned.
The crews that pilot the SPIPs are just as diverse, though they are segregated somewhat. An all Japanese crew mans one while the more diverse are relegated to the other ad do not share the same amount of screen time.
Honda's multicultural approach to the cast was two-fold; One it matched his ideals, and Two, It made the film an easier sell overseas.
The science is sketchy at best, though some of it was based on current ideas at the time. In particular the aliens anti-gravity beam was actually a freeze weapon. It was being talked about in the scientific circles at the time that gravity was a result of the movement of atoms and therefore if you lowered the temperature of an object to absolute zero and stopped all atomic movement, it would no longer be bound by gravity. Laughable by today's standards, but this was a theory in the late 50's. Gravity, or lack there of, continued as a sticking point in the science of the film. The movie acknowledges that there is no gravitational pull once you are in space, but as it turns out that so long as you are careful and don't jump around, you can walk and move around just fine. I suppose this was easier than trying to explain an artificial gravity system.
Though the science was faulty, the effects were not. Some stunning miniature work is seen throughout the film. From the launch pad of the SPIPs, to the moon rovers flying over the surface of the moon, some beautiful practical effects. It's easy to allow a little dodgy science and a bit of over-acting when the effects and matte paintings are so good.
The aliens, though powerful, are not particularly clever. Many opportunities to destroy the space center, the ships, and the crew are passed with little if any explanations. Why just vaporize your spy when you could just as easily destroy the entire base? You're right there! If you can remotely implant people with your mind controlling devices, why don't you do it more often and to people higher up the chain? Why stop at one dignitary and one astronaut?
Like I said, I hate to lump it in to the same group as the rest of the films that appear here. The effects are mind-boggling better, but it is these poor script choices that keep it firmly placed in what has come to be called a "B-Movie".