- Alan Smithee: The script is credited to David Agnew, a pseudonym often used by the BBC for work produced "in house" by contracted production team members. On this occasion it masks the authors Anthony Read and Graham Williams.
- Creator Backlash: Louise Jameson was not happy with Leela's exit; she wanted Leela to have a Dying Moment of Awesome. However, the production team were holding out hope that she'd stay on for next season up until the last minute.
- Creator's Favorite: Graham Williams loved the Sontarans, hence their re-appearance.
- The Other Darrin: Angus McKay was unable to reprise his role as Borusa, so John Arnatt took over.
- Troubled Production: Between labour and budget issues and the fact that it was a last-ditch replacement for an over-ambitious script, it's amazing this one ever got finished.
- What Could Have Been:
- Leela was supposed to be killed off in this episode, dying defending the Doctor against the Sontarans. Ultimately, the creators felt that this would traumatise children.
- Robert Holmes was supposed to write this story, but he declined, not wanting to return to the series having just left his post as script editor.
- Initially, it was revealed that the Time Lords were not native Gallifreyans, but rather had been permitted to construct their Citadel there in return for ensuring that the planet's populace lived in total comfort and security. It was these indigenous Gallifreyans that Leela met following her banishment.
- The Doctor's actions as President originally threw the Time Lords into open civil war, and part two ended with several rebellious Time Lords threatening to execute the Doctor (much as Andred does in the part three cliffhanger of the finished serial).
- The Vardans were also to betray the Doctor, ordering his annihilation at the close of episode three.
- Working Title: The Invaders of Time.
- Writing by the Seat of Your Pants: Louise Jameson was invited to continue her role. She was unsure whether she would stay until the end of recording, so a plot device had to be ready to allow her to stay on Gallifrey, hence her underdeveloped romance.
- You Look Familiar: Milton Johns (Castellan Kelner) had previously appeared as Benik in "The Enemy of the World" and Guy Crayford in "The Android Invasion".
Trivia / Doctor Who S15 E6 "The Invasion of Time"