Kenneth More was beginning to segue into comedy roles when he took on the character of William in this standard sci-fi parody by director Basil Dearden. William is an unsuccessful guinea pig for a medical group interested in researching the common cold when he is soon fired and offered a job by the nearby National Atomic Research Center. They figure anyone who could fail at being a guinea pig is just what they need. They con William into thinking he will continue his guinea pig career by testing out some equipment for them before they send a group of astronauts to the moon. What they neglect to tell him is that the testing will be done by actually sending him to the moon.
~ Eleanor Mannikka, All Movie Guide