When William describes Polly as being pretty enough "to make a bishop kick a hole in a stained-glass window", he is quoting (without acknowledgment) from Raymond Chandler.
Although he looks younger, Kenneth More was actually in his mid 40s when this was filmed, at least ten years too old to be a rookie astronaut in real life.
Charles Gray, Bruce Boa and Bernard Horsfall, who play the astronauts, have all appeared in James Bond films.