- Ability over Appearance: Bambera was originally envisioned as being from the Caribbean, hence the "shame" line. To Ben Aaronovitch's astonishment, the Manchester-born Angela Bruce was cast.
- Blooper: In a much less funny example, at the end of the cliffhanger where Ace is stuck in a water tank you can faintly hear Sylvester McCoy shouting "get her out!" This is because the special effect had malfunctioned, the glass had cracked and the water was approaching some exposed wires taped to the floor. If McCoy hadn't intervened Sophie Aldred would have been electrocuted; as it is, she escaped with just some cuts to her hands from touching the cracked glass.
- Creator Backlash: Ben Aaronovitch was very dissatisfied with the final production and felt the quality of the design and special effects let it down. He thinks "it doesn't work as a script, has crappy design and unhelpful music". He also didn't like the CND speech that Andrew Cartmel wrote. It was cut down, and Cartmel admitted that he overwrote it.
- Creator's Favorite Episode: Andrew Cartmel loves this story, naming it as one of his top three.
- Fatal Method Acting: Averted within a hair's breadth with Sophie Aldred. The water-tank booby trap Ace is trapped in wound up cracking under the water pressurenote and very nearly electrocuted her. She was only saved by the fact that Sylvester Mccoy noticed, swore briefly so that no one thought he was ad-libbing and yelled for the effects team to get her out. It later turned out that the tank's glass had not been made thick enough by the supplier from outside the BBC. The whole incident was filmed and later used in a BBC studio safety film. The footage was also used in a short documentary which can be found on the DVD release of this story.
- Saved from Development Hell: This story was Ben Aaronovitch's first-proposed one, but development took so long that "Remembrance of the Daleks", pitched later, was made in the previous season.
- Shoot the Money: John Nathan-Turner decided that Stock Footage of a helicopter simply wouldn't do, and that the show really needed to blow its budget on an actual one. So we get long, lingering shots of the helicopter transporting the Brigadier around.
- What Could Have Been:
- Graeme Harper was originally asked to direct. He had to decline, as he was busy with Boon. Andrew Morgan was also considered for the job, but depending on who you ask either he was busy as well, or the higher-ups vetoed his being hired for over-spending on "Remembrance of the Daleks".
- The Brigadier was supposed to die facing off against the Destroyer. This was approved by Nicholas Courtney, Andrew Cartmel and John Nathan-Turner. Ultimately, Ben Aaronovitch couldn't bring himself to do it.
- Lethbridge-Stewart was originally going to be promoted to General.
- The Destroyer of Worlds was envisioned as appearing as a well-dressed human man who later metamorphoses into a more monstrous form. To simplify the narrative, it was decided that the Destroyer should only appear in the latter guise. Similarly, the knights were intended to be dressed in futuristic combat gear that only looked like traditional armour at a glance, but this was dropped on the basis of cost.
- In the original version, Bambera was an American captain acting on behalf of a joint US-European initiative codenamed Camelot. Another key supporting character was Lavender Warmington, director of a heritage group called the Carbury Trust, while the Asian student befriended by Ace was named Thai. Ace herself wielded a newly-constructed sonic screwdriver. Morgaine ensorcelled Ace and planned to sacrifice her to the demon she raised otherwise, the demon would eradicate all life on Earth, thereby sealing the portal between this dimension and Morgaine's, and trapping A'tur. Lethbridge-Stewart called in an airstrike against the demon, and was mortally wounded; his death satisfied the demon, who then departed. Bambera killed Mordred to save Ancelyn, and a reawakened A'tur arrived, offering to bring Mordred back to life in return for Morgaine's obeisance. Bambera accompanied Ancelyn back to his dimension, while the Doctor would then continue travelling through time and space in honour of Lethbridge-Stewart.
- One alternative ending had the Brigadier deciding to accompany the knights back to their dimension.
- Freddie Jones and David Warner were considered for Peter Warmsly.
- Working Title: Storm Over Avallion, Lake Over Avallion, Pool of Avallion, Song of Avallion, Stormtroopers of Avallion and The Battlefield.
- You Look Familiar:
- Twenty-three years after her role as Sara Kingdom, Jean Marsh returns as Morgaine. There's possibly a bit of a nod here when Morgaine says that the next time she sees the Brig, she'll kill him — in her first appearance, set at least several centuries later than this story, Sara is under the impression her brother Bret (played by Nicholas Courtney) is a traitor, and kills him.
- June Bland, who had previously appeared in "Earthshock", returns as Elizabeth Rawlinson.
- Ling Tai had previously been an uncredited extra in "Warriors of the Deep".
Trivia / Doctor Who S26 E1 "Battlefield"