Getting to watch this film again after a full year, I discovered that two versions of it exist on cheapo DVDs from differing companies. (The differences may have been due to time demands from TV broadcast.) I'll call them A and B.
Version B is slightly longer than A; it includes more snippets from the original Russian sci-fi film (Planet of Storms) and fewer interjections from AIP. - Basil Rathbone disappears in the final third of the film. The color is better. The ending is more melodramatic. A crucial line from A disappears from B, yet a reference to it remains - the Robot John bidding farewell to his creator, Dr. Kerns - a humanizing touch that gives us to wonder about the development of the Robot as a character.
Of both versions, what must be said is they remain the only remnants Americans are likely to see of what appears to have been a fine Russian sci-fi film. The original cinematography is B-movie level, but quite good on that basis. The characters are fairly well-developed as individuals, which is surprising for a Russian film of the period. But then, the film develops along the lines of classical Romanticism, rather than the 'socialist realist' aesthetic approved in Russia at the time. The special effects are really not at all bad for the time. The story is one of discovery - of the joy of adventure that was once scientific exploration. I don't know how we lost this, considering that much of the earth's depths and all of outer space remain frontiers, but it is good to see it again, even if only in retrospect.
Review by winner55 from the Internet Movie Database.