- Creator Breakdown: Nicholas Courtney was suffering from depression at the time.
- Deleted Role: Although credited on-screen, Bill McGuirk (policeman) does not actually appear; his entire contribution was edited out prior to transmission. He had previously appeared in "The Enemy of the World".
- Executive Meddling: The story originally ended with the Doctor avowing that the Master would stay on Earth until I destroy him. Or until he destroys me. The BBC's Head of Serials Ronnie Marsh objected to this, as it made the Doctor seem too bloodthirsty. So it was changed to the Doctor saying that he's looking forward to their next encounter. Which makes him seem callous, considering the carnage.
- Fatal Method Acting: Averted. See below.
- First Appearance: Of the Master, Jo Grant and Captain Mike Yates.
- Inspiration for the Work: Robert Holmes claimed that the basics for the serial were all around him - a detergent company was giving away flowers, he remembered warnings about plastic bags killing children and plastic chairs and ugly troll dolls were all the rage.
- Recycled Set: When we see Farrell Senior and Mrs Farrell at their home in Episode Two, before the killer doll attack, part of the set furnishings for their sitting room includes a famous window (the round window) borrowed from the contemporary BBC television children's series Play School.
- Throw It In!: The stunt with the Auton Policeman rolling down the hill was not a stunt at all the car had hit the stuntman just fractionally too hard and sent him flying. Since the shot was awesome and since the stuntman wasn't seriously injured in his fall into the BBC Quarry, the director decided to leave it in. It leads to an extremely badass moment, since the Auton appears to get up immediately without even being stunned or disoriented, let alone damaged.
- What Could Have Been:
- In the original script, the Master's bomb went off when the Doctor tried to open the box by remote control. Terrance Dicks reworked it to make Jo more prominent.
- In the scene where the Troll Doll attacks Jo, Barry Letts had intended to film a shot of the doll running across the workbench. However Tommy Reynolds passed out due to the intense heat of being in the costume and so this idea had to be abandoned.
- Initially, the troll dolls played a much greater role in the story's climax, and explained the Master's interest in the circus, which would have been used to distribute the toys.
- Originally, it was the Brigadier who was strangled by the phone cord, as he tried to tell the police the truth about the troll dolls.
- In the original script, the daffodils (and the troll dolls) would be animated when the temperature reached a certain level a level which would be obtained thanks to a fortuitous oncoming heat wave in Britain. Feeling that this made the story's setting illogical it would make more sense for the Master to carry out his plan in a tropical locale it was decided to replace this with a broadcast activation signal.
- The Master originally used an Auton disguised as himself as a decoy in the climax.
- Working Title: The Spray of Death.
- Written-In Infirmity: Katy Manning injured all the ligaments in her foot when jumping out of a car and running across a quarry. Barry Letts added the scene where Jo twists her ankle to explain her limp.
- You Look Familiar:
- Harry Towb, who plays the unfortunate McDermott, had previously appeared in "The Seeds of Death".
- Michael Wisher, the young Rex Farrel, had also done uncredited voice work on "The Seeds of Death", and had previously appeared in "The Ambassadors of Death". He would later become the first to portray the Daleks' creator Davros.
- Roy Stewart (Strong Man) previously appeared as strong-man Toberman.
Trivia / Doctor Who S8 E1 "Terror of the Autons"