- Acting for Two:
- Casting Gag:
- In Japanese, Nightingale is voiced by Miyuki Sawashiro, the same actor who plays Mordred. So for the English dub, Nightingale's cameo in this show is voiced by Erica Lindbeck, who was the English voice of Mordred.
- Similarly, Da Vinci's voice is the same as Jeanne d'Arc in both languages, though Da Vinci's English debut was in the virtual reality game, not here.
- Continuing the trend, The Old Man or rather King Hassan is voiced by Kirei Kotomine in both languages as well.
- Jalen K. Cassell voices both Leff Lynor and the Mage King in English, matching with Tomokazu Sugita. In this case it's because Leff is a Demon Pillar, and the Mage King is the conglomerate hive mind of all the Demon Pillars, so in a way they're the same character.
- Invoked. Just before recording for Gilgamesh in the anime, Tomokazu Seki was hired by the Ancient Orient Museum in Tokyo to narrate a guided tour of the Gilgamesh and Heroes of the Ancient Orient exhibit. Fittingly enough, the script called for the narration to be incharacter as Gilgamesh and was made available as an audio CD, Recitation of The Epic of Gilgamesh: The Man that Peered into the Abyss
- Dueling Works: The Fall 2019 season presents three anime titles based on gacha games, namely; Azur Lane, Fate/Grand Order - Absolute Demonic Front: Babylonia, and the second season of Granblue Fantasy.
- Official Fan-Submitted Content: This is actually how the anime came to be. Back in January 2018, Fate/Grand Order held an in-game survey asking players what their favorite storyline from the game was, as well as what kind of future development they'd like to see in the franchise. The Babylonia chapter and "TV anime" scored first, respectively. Thus, a TV anime based on that chapter came to fruition.
- The Other Darrin: In the English dub of Fate/Apocrypha Merlin was voiced by Khoi Dao. Here he's voiced by Robbie Daymond.
- Promoted Fanboy: A big reason why Aniplex was able to get so many famous animators onto the project is that several of them were already massive fans of Fate/Grand Order and leapt at the chance to animate their favorite scenes from the game.
- Real-Life Relative: The Japanese voice actors of Dr. Roman and Da Vinci are married, which makes the dynamics of these two very interesting and heartwarming.
- Recast as a Regular:
- Robbie Daymond previously voiced Issei Ryudo and Atrum Galliasta from the animated adaptation of Fate/stay night [Unlimited Blade Works] before being cast as Merlin.
- Billy Kametz previously voiced Male Hakuno Kishinami in Fate/Extra Last Encore before being cast in a cameo role as Wolfgang Amadeus Mozart.
- In an inverse to Kametz, Chris Hackney previously played minor supporting character Li Shuwen but plays Marisbury Animusphere here, who has a significant time in the spotlight for episode 0.
- Ditto for Marianne Miller who previously voiced the young Kiritsugu Emiya from the animated adaptation of Fate/Zero before being cast as Enkidu.
- Lauren Landa played Luviagelita Edelfelt for the final episode of Fate/stay night [Unlimited Blade Works] and Celenike Icecolle Yggdmillennia in Fate/Apocrypha, and is now Siduri here.
- Ray Chase previously voiced Lancer of Black/Vlad III in Fate/Apocrypha and now voices Leonidas I.
- Laura Stahl previously voiced Leo Harway in Fate/Extra Last Encore and now plays Ushiwakamaru.
- Role Reprise: For the dub, all actors from First Order and the VR game have returned to voice the same characters. And aside of Merlin above, all the actors that voiced the previous iterations of the Servants/characters return (David Vincent as Gilgamesh, Melissa Fahn as Ana (little Medusa), Mela Lee as Ishtar (in Rin Tohsaka's body), and Julie Ann Taylor as Jaguar Warrior (in Taiga's body). Cameo roles are reprised as well: from Fate/Extra Last Encore, Cassandra Lee Morris returns as Nero and Jessica Gee-George as Drake.
- Relationship Voice Actor:
- In the Japanese version:
- In the English dub:
- Talking to Himself: Episode 13 has Ishtar talk with Ereshkigal who as stated on this page is voiced by the same voice actress due to both of them possessing Rin Tohsaka's body.
Trivia / Fate/Grand Order - Absolute Demonic Front: Babylonia