- The Cast Showoff: Jon Pertwee recalled that he persuaded Barry Letts to include the trikes seen in the story, reflecting his love of vehicles. However he considered the chase sequence involving them to be "one of the more dangerous stunts that I had insisted on doing" during his time on the series.
- Creator Backlash: Both Jon Pertwee and Katy Manning, although acknowledging the story as a fan favourite, cited it as the nadir of their Doctor Who experience. Chief amongst their complaints was the unreality of the Dalek attack on Auderly House, which they found to be a pathetic affair. The paltry number of Daleks for the attack, which Pertwee estimated at two, could not reasonably have launched a fearsome end battle.
- Keep Circulating the Tapes: The BBC have refused to make the original version of the story available on streaming media platforms, with only the 2011 DVD re-edit available. Fortunately, for those who don't mind physical media, the DVD itself does include the originally-transmitted version.
- Old Shame: Needless to say, the BBC does not like talking about the original version of this story, and with good reason given how shoddy its attempt at bringing back the Daleks was (for one, they only had three usable props at the time and had to rely on inexperienced voice actors without ring modulators available); they jumped at the chance to reshoot and re-dub portions of the story in 2011 when they got the chance, and this edited version is the only one officially available on streaming services, with the broadcast version being relegated to the DVD release alone.
- Recycled Script: This was apparently a rush adaptation from The Outer Limits script "Soldier".
- What Could Have Been:
- Again, Terry Nation was unable to write this story, as he was working on The Persuaders!
- Originally the serial was to end with a scene where the Doctor and Jo went back to the lab, and saw their earlier selves working at the TARDIS console. However, director Paul Bernard refused to film it, saying "Once it's over, it's over". Script editor Terrance Dicks would later restore the scene when he novelised the story.
- Episode Four was originally intended to include a confrontation between the Doctor and the Daleks, in which the Daleks explained how they destroyed those of their number who were infused with the Human Factor in "The Evil of the Daleks" and turned their attention to conquering Earth by means of time travel. But this scene had to be edited out, due to the episode overrunning. On the bright side, the omission of this expository moment ended up saving the episode from the pitfall of Continuity Lockout (which would've led to even further criticism for an already panned serial), as "The Evil of the Daleks" was five years old by this point and doomed to Missing Episode status.
- Originally, the Ogrons were the main bad guys of the story instead of the Daleks. When problems arose with the original season finale, which actually was meant to include the Daleks, this story was rewritten to incorporate the Daleks, with the Ogrons instead turned into the Daleks' mooks.
- Working Title: The Ghost Hunters, Years of Doom, The Time Warriors and Ghosts.
Trivia / Doctor Who S9 E1 "Day of the Daleks"