The slang term for the Solonians was originally going to be "munt" instead of "mutt" and was changed by Terrance Dicks. The common reason given for the change is that "munt" was an authentic derogatory term used amongst the white settlers of South Africa in reference to the indigenous black population.
While this is partially true, this was only the secondary reason. In the BluRay commentary for the story, Dicks recalls that head of serials Ronald Marsh asked to see him, being outraged at the possibility of the word "munt" being said in a 5:50pm timeslot, particularly a line about the Marshall being "munt mad". Although Dicks isn't explicit in his explanation, the clear inference is that the term sounded far too much like a derogatory swear word.
While this is partially true, this was only the secondary reason. In the BluRay commentary for the story, Dicks recalls that head of serials Ronald Marsh asked to see him, being outraged at the possibility of the word "munt" being said in a 5:50pm timeslot, particularly a line about the Marshall being "munt mad". Although Dicks isn't explicit in his explanation, the clear inference is that the term sounded far too much like a derogatory swear word.
This serial was written as a negative commentary on Apartheid.
The opening shot of the story features a bedraggled, hermit-like bearded figure (Sidney Johnson) shambling out of the mist towards the camera. Both fans and Jon Pertwee alike have compared the scene to the "It's" man at the start of most episodes of Monty Python's Flying Circus (1969). The DVD release of the story also references this in the information text commentary.
This episode takes place on Solos in the 30th Century.