William Hartnell suffered a bereavement while working on the story: the death of his Aunt Bessie, who had looked after him during his troubled childhood. Unfortunately, the tight recording schedules prevented him from taking time off to attend her funeral. This led to him becoming difficult during production, refusing to speak to actors Max Adrian or Francis De Wolff and declaring director Michael Leeston-Smith a "fool".
William Hartnell was unhappy making this serial. His health had begun to deteriorate, with his arteriosclerosis making it more difficult for the actor to remember his lines. Furthermore, Hartnell was unhappy by what he saw as the Doctor's diminished role in the scripts. He feared that he was being upstaged by prominent guest stars, including Francis De Wolff and especially Max Adrian.
William Hartnell was bruised after being struck on the shoulder by a camera platform, although he soldiered on through the taping.