The Medved Brothers, back in the 1980s, listed "Robot Monster" among the 50 worst films of all time. It deserves that accolade. With dialog (serious dialog) like "I am not a human...I am a Ro - Man." said by an actor in a gorilla suit (George Barrows, the actor in the gorilla suit, actually played a gorilla in another film in a few years - it must have been one of his so-called talents), this is the nadir (I almost said Nader, for the star of the film) of bad movie making. It is poverty-row movie making.
I notice the name of Ed Wood mentioned in some of the reviews here. Wood never did a good film, but there was (I believe) a man in Wood who really felt he had some type of cinematic vision. It was not a trained one - it was quite inept. But if you look at what Wood is attempting to do in some of his films in the 1950s (tackle cross-dressing in "Glen Or Glenda", for example) one can vaguely sympathize with his having some concepts but no talent to really put them across. I think that is why Wood has somehow become a negative Hollywood legend.
That can't be said for Phil Tucker. He never seems to have gotten the bug of making just monster movies. When Wood planned "Plan Nine From Outer Space", he did intend to comment about the danger of our arms race (it comes out ludicrously in the film, but it is there). Tucker could not do that. He just could push together the typical hack like conventions to muddle through. So he has the heroine "vamp" the "Robot Monster" no matter how idiotic it looks. I have never seen Tucker's "Cape Canaveral Monster", which was his last film, but I suspect it is just a slightly smoother version of the bilge he put together here.
I do have one suspicion that makes me think this film was just a poverty row quickie without rhyme or reason (not like Wood's type of schlock which he actually agonized over at home and when filming). I noticed while looking through the credits the backgrounds and fates of the different players. The only one who went anywhere in the 1950s was George Nader, who actually may have done a good performance in one film ("Away All Boats"), but whose career petered out due to his getting involved in a homosexual scandal. He ended doing television in Germany. This film actually was his first real "lead" role. Barrows never had as "important" a role in a film as "Robot Monster". Selena Royle had done some important films in the 1940s but she was blacklisted (possibly unfairly). She did make a successful second career in Mexico (which I am glad about). John Brown was also a victim of the blacklist. Few know of it today (despite the decades of reruns of the old Burns and Allen television show) but he was on the show for a few months in 1950, replacing Hal March as the neighbor Harry Morgan. Brown, who had a distinguished career in radio comedy shows like "The Life Of Riley", was replaced by producer George Burns when his sponsor pointed out that Brown was suspected of communist sympathies. He would be replaced by Fred Clark. It is the shows with Clark and later Larry Keating that we have seen to this day. Brown kept working when he could. He died in 1957. Claudia Barrett's career died out in the 1960s. As for the two child performers, Gregory Moffett acted until about 1956, and Pamela Paulson never made another film in her life. John Mylong usually played bit-parts in films, frequently (during World War II) as Nazis (he's in "The Hitler Gang"). He does play Eddie Duchin's (Tyrone Power's) father in "The Eddie Duchin Story".
In short this cast is strictly from hunger in terms of name recognition. All, that is, except the future acting "success" Nader, and the past success Royle, and this is a rung up for the former and a last chance for the latter. When Tucker cast this picture he grabbed people who were desperate to be in anything that offered them a chance to have a speaking part of any type, no matter how silly. Now compare this with Woods - he uses Bela Lugosi again and again, because he recognizes that Lugosi has name recognition with the public, and some degree of talent left as well (though drug addiction made the latter even weaker than it was). He also uses some character actors like Lyle Talbot who have been around for awhile (the Medveds don't think highly of Talbot, as he seems somewhat humorless - actually at about the same time he worked for Wood, Talbot appeared as himself in a comic series of rivalry confrontations with Bob Cummings on the latter's successful television series "Love That Bob!"). Wood also used local television stars like Vampira and Cresswell the mentalist, and Tor Johnson the Swedish wrestler in his films. In short Wood looks like he made an effort to choose his cast with something approaching thought (for effect, for what he thought was talent). The results might have been laughable, but it showed a type of care. Tucker didn't show that. So for all the cheesiness of Wood's works, we can admire the attempt. We can't with Tucker.
The most memorable moment of this movie? The booming voice deciding to unleash prehistoric monsters on the planet (we see some kind of lizard roaming a small set - it's supposed to be a tyrannosaur?). I think it was memorable because it came about two minutes before the film ended.
Review by theowinthrop from the Internet Movie Database.