The Drahvins were originally intended to be male. It was Verity Lambert who suggested that they be female.
The stars greatly disliked the scripts for this serial. Things got so heated that John Wiles threatened to fire William Hartnell. Maureen O'Brien's complaints led to Wiles dismissing her in The Myth Makers.
This episode was wiped by the BBC and no copy of it is known to exist.
This Episode has the distinction of holding the most recovered Footage of a missing Episode of Doctor Who, a single 6 minute excerpt survives from this episode, where as most other surviving clips from any other missing episodes are about 10 seconds or less.
Although Verity Lambert is credited as Producer, this is the first story that John Wiles is in fact the holder of that role, although he was very un-popular with most of production team and even the regular actors. Hartnell felt that he'd forced Lambert (whom he greatly admired) out of the role, whilst Peter Purves sided with Hartnell due to the two's friendship. Wiles also stopped the practice of tele-snaps being taken as he preferred to put the money elsewhere, and as such the missing episodes that were made under John Wiles (Galaxy 4 Episode 1 - The Celestial Toymaker Episode 4) have no Offical BBC telesnaps. Peter Purves has said in hindsight that, "John Wiles did me dirty", as most of episodes took place during this time.