- Creator Backlash: Tom Baker was unhappy with the fact that the final image that viewers would see of his Doctor would be of him lying prone, being photographed from above. Russell T. Davies evidently agreed with Baker's viewpoint, and while in charge of the 2005 revival mandated that all regenerations were to be depicted with the Time Lord stood at his or her feet.
- Enforced Method Acting: Possibly unintentional. When the director ordered Peter Davison to sit up, he did so in a tone that made Peter think he was doing something wrong. His look of surprise is genuine.
- First Appearance:
- Of Tegan Jovanka.
- The Cloister Bell is introduced.
- Technology Marches On: The highly advanced aliens who are holding the world together with pure mathematics use bubble memory. As the Doctor puts it, "Bubble memory is non-volatile. Remove the power and the bit patterns are still retained in tiny magnetic domains in these chips!" The writer was a computer scientist and bubble memory was quite cutting edge in 1981. Nowadays, not so much, as it's only remembered as an early precursor to modern-day flash memory.
- Wag the Director: The Doctor was supposed to scream as he fell to his death. Tom Baker disagreed, as he felt it was unheroic.
- What Could Have Been:
- Either Sarah and/or Leela were considered to return in order to give a familiar face for the Fourth Doctor to go through his regeneration story and ensure a smooth transition. Elisabeth Sladen and Louise Jameson declined to return, so Nyssa and Tegan were brought in.
- Peter Cushing, Michael Gough, and Peter Wyngarde were considered for the Monitor.
- Michael Sheard was considered for the Detective Inspector.
Trivia / Doctor Who S18 E7 "Logopolis"