For each episode, the story title, writer credit and episode number blur in over footage of volcanoes and flowing lava.
The Doctor (Jon Pertwee
) tells the Brigadier (Nicholas Courtney
) that he was present at the eruption of Krakatoa on August 27, 1883. It was later revealed in the Doctor Who (2005)
" that the Ninth Doctor (Christopher Eccleston
) was also present at these events.
Sheila Dunn (Petra Williams) was the real life wife of director Douglas Camfield.
This episode attracted 5.7 million viewers on initial broadcast.
The Doctor: (to Professor Stahlman) Well, I'll tell you something that should be of vital interest to you.
Professor Stahlman: What's that?
The Doctor: That you, sir, are a nitwit!
In several sequences, it is clear that both Nicholas Courtney and Olaf Pooley are wearing false facial hair. While the Brigadier and Professor Stahlman have a moustache and a beard respectively, their counterparts in the parallel universe are both clean-shaven.