It has been estimated that 55 deaths occur on screen in this serial.
The repair to the Chameleon Circuit was in part a publicity effort by John Nathan-Turner to drum up more interest in the series. He hinted publicly that it might be a permanent development, but never pursued the idea beyond this story.
This story introduced the Sixth Doctor's spiritual equivalent of the sonic screwdriver, a portable sonic lance, after the screwdriver had been written out in The Visitation: Part Three (1982).
Nicola Bryant was uncomfortable wearing her tight pink leotard on location because it was very cold but producer John Nathan-Turner thought it would be appreciated by the men in the audience.
This is Terry Molloy's only on screen appearance in Doctor Who (1963) playing a character other than Davros.