* AnimeFirst: Unlike other anime that were made before a manga adaptation for it was announced, the anime didn't get a manga adaptation after it premiered. But it did received a comic book adaptation by Archie Comics after it premiered.
* CrossDressingVoices: Creator/MikePollock voices Ella in the English dub.
* ExiledFromContinuity: Despite being very similar to the games in story and characterization, specific elements created for the series are not allowed to be used in other Sonic continuities due to copyright issues. The closest exception was a cameo of the series promo art in an optional side quest in ''VideoGame/SonicAdventure DX'', and a brief crossover between this series ''Sonic X'' and ''ComicBook/ArchieComicsSonicTheHedgehog'' (the former being a series that was given a legally mandated embargo on using elements from several ''Sonic'' series, including ''Sonic X'', and an event that is likely the reason why Sega will not allow Archie to reprint their ''Sonic X'' comics).
* FanNickname: Cosmo's species never really had a nickname until someone nicknamed them "Seedrians" for their plant like features.
* {{Feelies}}: The "Project: Shadow" DVD included a card from the ''Sonic X'' card game.
* KeepCirculatingTheTapes: The show aired reruns for a ''long'' time. Despite this, according to Ian Flynn, {{Creator/Sega}} [[ExecutiveMeddling apparently doesn't want]] [[ComicBook/SonicX the comics based on the show]] [[ExecutiveMeddling to be reprinted]], if some sources are to be believed.
** The show may have stayed alive through television reruns, but when it came to DVD releases, there was only incomplete releases from 4kids and Funimation until Creator/DiscotekMedia decided to license the show for a DVD release. Even still, Discotek currently only has plans for releasing the 4Kids dub [[note]]This is due to 4Kids themselves not supplying the scripts for the subtitled version that was streamed on Hulu, meaning that a sub-only (or even a re-dub based on the Japanese subs) release would require ''a complete recreation from scratch''[[/note]], meaning those who are hoping for an uncut release are out of luck, or at least will have to wait until Discotek decides to put out such a release, or until they give the license to someon else, like Website/{{Crunchyroll}}.
* NoExportForYou: Inverted? The last season only aired ''outside'' Japan, despite a full Japanese voice track being produced.
* TheOtherDarrin: Unlike the games in 2003, the Anime featured different voice actors from the Creator/FourKidsEntertainment line up such as Creator/JasonGriffith as Sonic and Shadow, Amy Palant as Tails, Creator/DanGreen as Knuckles, Creator/LisaOrtiz as Amy, and Creator/MikePollock as Dr Eggman. They would later replace the game voices as the official voice cast until 2010, when all but Mike Pollock would be replaced with the current voice cast.
** While most of the Japanese voice actors were retained from the games series, Creator/JojiNakata did not reprise his role as E-102 Gamma (despite providing the voice work for Dark Oak in the third season of the anime). Instead Naoki Imamura (who voices E-123 Omega in the games) took the role.
** After Creator/ShunYashiro's death that same year the anime began airing, Creator/TakashiNagasako began taking over as Big the Cat in the anime and in the games.
** Tails on the other hand was originally voiced by Kazuki Hayashi in Videogame/SonicAdventure and Atsuki Murata in Videogame/SonicShuffle and Videogame/SonicAdventure2, but is now voiced by Creator/RyoHirohashi in the anime and in the games.
** Pachacamac was originally voiced by Creator/ToruOkawa in Videogame/SonicAdventure, but is now voiced by Toshihiko Nakajima in the anime.
* RelationshipVoiceActor: [[Creator/SanaeKobayashi Chris]] and [[Creator/KojiYusa Shadow]] are [[Anime/YuGiOhGX Alexis and Atticus]] and [[Manga/{{Karneval}} Mine and Tsukitachi]].
* SheAlsoDid: Chris's voice actress, Creator/SuzanneGoldish, would also go on to direct a few anime dubs with the L.A-based Creator/{{Studiopolis}}, including ''Manga/{{Bleach}}'', ''Anime/{{K}}'', and ''Manga/SailorMoon'' (2014 re-dub).
** Chris' Japanese voice actress. Creator/SanaeKobayashi. would also play Allen Walker in Manga/DGrayMan, a manga in which Creator/TMSEntertainment would later adapt into an anime.
* TalkingToHimself: In Spain, Rafael Alonso Naranjo Jr. was Sonic and Vector.
** In English speaking territories, Jason Adam Griffith voiced both Sonic and Shadow.
* WhatCouldHaveBeen:
** ''Sonic X'' originally looked like [[http://www.youtube.com/watch?v=L7AqlIp5evA this]].
** While not too different from the how the show actually turned out, there were a few elements that were definitely scrapped or changed from [[http://www.youtube.com/watch?v=7L7ti-tw8ro&feature=related the second pilot]].
** One particular change from the second pilot was Super Sonic, [[http://www.tssznews.com/2015/09/22/takashi-iizuka-nazo-is-super-sonic/ who was originally going to have a silver coat and different quills]]. This was scrapped for the the more recognizable yellow design.
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