Only three episodes from this story are still in the BBC Archive, they are episodes 2, 5 and 10.
This episode was the first of a serial called "The Daleks' Master Plan" which ran over twelve consecutive Saturday evenings and concluded with Destruction of Time (1966). At twelve episodes, it was the longest Doctor Who (1963) serial for over 20 years until The Trial of a Time Lord: Part One (1986), which had fourteen episodes.
This story marks the "Doctor Who" debut of Nicholas Courtney, who would go on to play Colonel (later Brigadier Sir) Lethbridge-Stewart, one of the most popular recurring characters in the series' history. Douglas Camfield cast him after remembering his audition for King Richard in "The Crusade".
The already fragile relationship between William Hartnell and John Wiles was also degenerating further, not helped by the deteriorating state of the star's health. Wiles was becoming increasingly exasperated by Hartnell's tendency to deviate from his scripted lines, and had to deal with a brief crew strike arising from a dispute between Hartnell and his dresser. Things got so bad that The Manchester Evening News reported that Hartnell would be quitting Doctor Who (1963), although this did not transpire.
This episode takes place on Kembel in 4000.