Director Douglas Camfield used part of the same incidental music score he also used on the 1968 Doctor Who serial "The Invasion".
This is the only episode of the third season of Out of the Unknown (1965) that still exists in the BBC archives.
Director Douglas Camfield had recently cast Peter Halliday in the Doctor Who serial "The Invasion". He would later cast Lillias Walker in the Doctor Who serial "Terror of the Zygons".