- Cast the Runner-Up: Christopher Gable (from the Ken Russell film adaptation of The Boy Friend) was originally offered the role of Salateen. Graeme Harper wanted him for Jek but didn't think he would accept, as he'd be hidden behind a mask for the whole story (except for the hideous prosthetics of the Phantom of the Opera reveal); but Gable wanted the challenge and the larger role.
- Creator's Favorite Episode: Peter Davison named this as his favourite serial (claiming that if he'd gotten more stories of this quality earlier in his run he would have wanted to stay on longer), Nicola Bryant named it as her favourite from her first series and John Nathan-Turner named it as one of the highlights of his tenure.
- Deleted Scene: Recording was interrupted by a strike, which caused a serious delay in the filming of the serial. As a result, two sequences had to be cut. The first scene would have featured the Doctor and Peri at the opening of the story in the TARDIS. The Doctor was to explain to Peri the reason for their visit to Androzani Minor. Apparently, as a boy, the Doctor had started a "blown glass bottle collection", which was made from the sand of different planets. He had lost his Androzani bottle and decided to return there to retrieve some more sand. It was in this scene Peri was to say "You're such a pain, Doctor." However, when the final cut of the serial was made, it had been discovered that certain lines of dialogue (like the Doctor professing that "I am not a pain" and Peri's comments about needing sand to "make some glass") alluded to the cut sequence. To rectify this, Peter Davison and Nicola Bryant voiced over part of their conversation while the TARDIS materialises from outer space to the planet. The second scene to be cut would have featured the Doctor battling with the magma beast in episode four which, under the circumstances, the serial is probably better off without.
- Enforced Method Acting: This story was rife with on-screen mishaps that ended up causing minor injuries to Peter Davison, who would later jokingly claim that the staff were actually attempting to kill him.
- During a scene in which Sharaz Jek backhands the Doctor, the mask Christopher Gable was wearing impaired his vision enough to make him legitimately strike Davison by mistake.
- As the Doctor carries Peri back into the TARDIS at the end of the story, he flinches at a nearby mud burst. This is because the explosion was prematurely triggered by the technicians, shooting sand into Davison's eyes and forcing him to recoil in pain.
- Throw It In!: The scene where Morgus faces the camera directly and speaks out his inner thoughts came about from John Normington misunderstanding the stage directions he was given. However, everyone liked the theatrical feel of it and that take was left in the episode.
- Troubled Production: This was one of several eighties stories affected by strike action at the BBC (in this case, by the scenery shifters). It lost one of its studio sessions, and one of the sessions for the following serial, "The Twin Dilemma", had to be reassigned to it (which might have resulted in the cancellation of "Dilemma", although in the event John Nathan-Turner was able to secure an extra slot for that story on the grounds that it was important as the new Doctor's first full story; however, it also contributed to the poor working climate that resulted in "Dilemma" being recklessly rushed out the door).
- What Could Have Been:
- Tim Curry, David Bowie and Mick Jagger were offered the role of Sharaz Jek. Also considered were Derek Jacobi and John Hurt (both of whom would go on to appear in the revival series decades later as the Master and the War Doctor, respectively). Of these five, David Bowie is the only one whose refusal we actually know the reason for: the scheduled taping dates conflicted with his Serious Moonlight tour.
- Ian Holm was offered a role (most likely Morgus).
- Michael Gambon was considered for Sharaz Jek and General Chellak.
- Brian Cox was considered for Sharaz Jek and Salateen. He would later play Sydney Newman in An Adventure in Space and Time.
- Julian Glover was in the running for Sharez Jek, Morgus, and Chellak.
- Warren Clarke was considered for Stoltz.
- Steven Berkoff was considered for Sharaz Jek, Stoltz and Chellak.
- Martin Jarvis and Michael Jayston were considered for Sharaz Jek and Morgus.
- Donald Sumpter was considered for Salateen.
- Graeme Harper hoped to bring Michael Craze back to play Krelper, only to be vetoed by John Nathan-Turner.
- In the original script, the Doctor did not regenerate after succumbing to spectrox toxaemia, but simply because of the damage his body sustained in combatting Stotz and his gunrunners.
- Working Title: Chain Reaction.
Trivia / Doctor Who S21 E6 "The Caves of Androzani"