- Cast the Runner-Up: In addition to Dalek voicing duties, Roy Skelton was supposed to play Davros, but he was busy with Rainbow.
- Creator's Favorite Episode: Tom Baker named this as one of his favourite serials, while Terry Nation thought it was the best script he wrote for the series.
- First Appearance: Of Davros.
- Inspiration for the Work: According to Barry Letts, this story came about due to the fact that, when he was still serving as producer, he asked Terry Nation to write a new Dalek story but the two drafts that Nation submitted were identical to what he had previously written for "Planet of the Daleks" and "Death to the Daleks". So Letts suggested that he could explore "the genesis of the Daleks" thus giving Nation the idea, and the title, for this story.
- Prop Recycling:
- The three active Dalek props used in the serial were originals from the 1960s, and their wear was covered by new paint. Five "dummy" Daleks which could not be operated were also used.
- Some of the Thal guns were re-used props from "Galaxy 4".
- The creature Harry and the Doctor glimpse at the end of Part Two was mainly a reused Ice Warrior costume.
- The Thal rocket ship was a reused model from "The Ambassadors of Death".
- Spared by the Cut: There was a cut scene showing Davros' life-supported system indicating that he survived being shot by the Dalek. It was decided to leave his fate ambiguous, though it was agreed he was far too good a villain to be killed off in one story.
- What Could Have Been:
- Terry Nation's original idea for the story was rejected by the producers for being too much like his previous Dalek stories. It was Terrence Dicks who suggested he do an origin story for the Daleks.
- The Doctor's meeting with the Time Lord originally took place in a lush garden. David Maloney and Philip Hinchcliffe disliked this idea and changed it.
- The role of a Kaled officer named General Greiner was subsumed by Ravon, while Sevrin was paired with a second Muto named Marrass.
- Bettan was originally a man.
- Terry Nation intended the Mutos to be much more bestial in appearance, their forms usually hidden by their rags.
- Episode Three originally contained a subplot where Sarah contracts radiation poisoning, recalling a similar story strand in "The Daleks".
- Episode Five originally had more action in the Dalek incubator room and ended with the Doctor's question of whether he had the right to destroy them.
- The Thal soldiers were originally supposed to be boys aged 15 or 16 to illustrate the youth of those fighting in the war, but this was later changed to make them appear more mature.
- Word of God: Russell T Davies considers the mission that the Doctor is given by the High Council, namely attempting to remove the Daleks from the timeline, to be the first shot in the Last Great Time War.
- Working Title: Daleks Genesis of Terror.
- You Look Familiar:
- Michael Wisher, the actor for Davros, was previously one of the regular voice actors for the Daleks. He'd also appeared in "The Ambassadors of Death", "Terror of the Autons" and "Carnival of Monsters".
- Peter Miles (Nyder) had previously played Dr. Lawrence and Professor Whitaker.
- Hilary Minster plays one of the Thal soldiers. He had played another in "Planet of the Daleks".
Trivia / Doctor Who S12 E4 "Genesis of the Daleks"