* ActingForTwo: Creator/BrittneyKarbowski as Misaka and the other clones. {{Justified|Trope}} since the latter were cloned based on her DNA.
* AscendedFanNickname: Heaven Canceler's FanNickname, Dr. Gekota, is acknowledged when Saten mentions how the doctor looks like Gekota.
* FlipFlopOfGod: In the beginning of the [[Literature/ACertainMagicalIndex Index]] novel and anime, Mikoto fires a railgun which passes by Touma but in the Railgun manga drawn by Motoi Fukuyama, she fires the Railgun at him which he stops using Imagine Breaker. Unfortunately, this caused some backlash with fans since it is contested by the fandom if this is possible. To avoid this contradiction, the Railgun anime has the events that lead to the Railgun incident {{Retcon}} to an earlier date before the time of the first Index arc.
* HeyItsThatSound: In episode 16 of the first season of the anime, the cellphone of Kurozuma Wataru (who is actually [[spoiler:Hebitani Tsuguo]] goes off. If you listen to the ringtone you find that the song playing is auld lang syne.
* OvertookTheManga: The reason the first two seasons had original stories. During the first season only the Level Upper arc was done and the Sisters Arc was ongoing. For ''Railgun S'' the Sisters Arc was done but the Daihasei Festival Arc was ongoing. With the seven year gap between ''Railgun S'' and ''Railgun T'', it meant the latter could adapt two arcs, the Daihasei Festival and Dream Ranker arcs, with no need for a filler storyline.
* PigeonholedVoiceActor:
** Mugino isn't the [[Anime/DogDays first]] BloodKnight or the [[VisualNovel/UminekoWhenTheyCry first]] AxCrazy LadyOfWar Creator/AmiKoshimizu has played.
** Mitsuko Kongou isn't the first time Creator/MinakoKotobuki played an {{Ojou}} [[Manga/KOn in a series that stars a lot of girls.]]
* PlayingAgainstType:
** Creator/ColleenClinkenbeard as the psychopatic Therestina Lifeline.
** Creator/BradHawkins and Katsuyuki Konishi as Wataru Kurozuma. An Anti-Hero who likes a good fight.
** Sayumi Suzushiro and Emi Lo as Rakko Yumiya. A nice girl who turns out to be a psycho DarkActionGirl.
* ReleaseDateChange: ''A Certain Scientific Railgun T'' had the unfortunate timing to air during the UsefulNotes/CoronavirusDisease2019Pandemic, resulting in where four episodes having delayed airings for a week or a two, followed by a two month hiatus upon the completion of the season's first StoryArc with the 15th episode.
* SequelGap: Season 2 of the anime ended in 2013, but there wasn't a new season until 2020.
* StarMakingRole: Three of them:
** For Creator/SatomiArai as Kuroko. It even landed her a "Best Supporting Actress" trophy for the 2010 Annual Voice Actor Awards.
** One of Creator/KanaeIto's first few roles that shot her up as a noteworthy voice actress was Ruiko Saten.
** In the English dub, Kuroko served as this for Creator/AlisonViktorin.
* TheOtherDarrin:
** For Railgun S, Lindsey Seidel voiced Aomi Yanagisako instead of Maxey Whitehead.
** In the English dub of Railgun T:
*** Creator/AmandaGish takes over voicing Kinuho Wannai from Creator/KristiKang.
*** Creator/MorganBerry replaces Barrett Nash as Misuzu Misaka.
*** Creator/MikaelaKrantz replaces Teri Rogers as Misaki
* WhatCouldHaveBeen:
** The author Creator/KazumaKamachi originally intended for Kuroko Shirai to be the main protagonist, due to being only told that there was a demand for a science-side sidestory manga. But the production staff clarified that the actual request was for Mikoto to star in the manga.
** Creator/KazumaKamachi's outline for the Daihasei Festival Arc orginally didn't include Gunha Sogiita. However, the manga-ka needed another month to get ready to start on the arc, so resulting in the plot of Chapter 43, where Gunha and Misaki end up being the Level 5s chosen to speak at the festival's opening. Because of this, Gunha would get a larger role in the arc's climax, fighting alongside Touma against the possessed Mikoto.
* VisualPun: In Accelerator's first battle (chronologically), MISAKA 00001 is holding what appears to be a variant of the Colt XSE known as the Rail Gun.
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