* ActorAllusion:
** Kirito is one to Creator/BrycePapenbrook: he was once a virtual reality gamer named Shugo Kunisaki of ''Manga/DotHackLegendOfTheTwilight'' who happens to have the same problem with the video game system as Kirito. Kirito's Spriggan avatar also looks like Rin Okumura of ''Manga/BlueExorcist'', another character voiced by Creator/BrycePapenbrook.
** This is not the first time Creator/CheramiLeigh voiced an ultra-{{badass}} ActionGirl [[LightNovel/ShakuganNoShana who mainly fights with a sword]].
** Stephanie Sheh also voiced another adorable [[Manga/KOn Yui]].
* DeadStarWalking: Creator/NobuyukiHiyama voices Diabel, a charismatic man who was able to gather a large group of people to hunt down the boss of the first floor. He dies in the same episode.
* FanNickname: ...or rather detractor nicknames:
** "Waifu Art Online", specially the Aincrad arc (curiously, this is the only nickname that is not necessarily derogatory).
** "Imoto Art Online" for the Fairy Dance arc. Also in the mix are "Harem Art Online", and "Incest Art Online".
** The GGO arc (''Sword Art Online II'' for the anime) has been jokingly referred to as "[[MaleGaze Sinon Ass]] Online".
* FlipFlopOfGod: There is a little bit of this regarding whether Kirito and Sachi had romantic feelings for each other or not.
* HeyItsThatVoice:
** The original Japanese version:
*** Creator/KoichiYamadera voices Kayaba. It's also amusing in hindsight, because he's using [[GhostInTheShellStandAloneComplex Togusa]]'s voice for a villain who wouldn't be out of place in that verse.
*** Creator/ToruOkawa is using his [[GhostInTheShellStandAloneComplex Saito]] voice for Heathcliff. There's also just enough of [[TearstoTiara Demon King Arawn]] in there to make you sit up and take note.
*** [[LightNovel/BodaciousSpacePirates Princess Gruier Serenity]] is [[HarukaTomatsu Asuna]].
*** Creator/MegumiToyoguchi plays an EvilIsSexy guild leader.
*** Creator/TakehitoKoyasu plays Sugou.
*** Creator/AyanaTaketatsu plays Suguha. [[OreNoImoutoGaKonnaNiKawaiiWakeGaNai My Little Sister Can't Be This Cute]] indeed.
*** HiroakiHirata [[Anime/TigerAndBunny (Wild Tiger)]] is Klein.
** The English dub:
*** Creator/BrycePapenbrook as Kazuto "Kirito" Kirigaya.
*** Creator/CheramiLeigh as Asuna Yuuki.
*** Creator/CassandraLee as Suguha Kirigaya/Leafa.
*** Creator/ChristineMarieCabanos as Keiko "Silica" Ayano.
*** SarahWilliams as Lizbeth.
*** Creator/PatrickSeitz is Agil.
*** Creator/StephanieSheh is Yui.
*** KaijiTang is Schmidt.
*** Creator/KyleHebert is both Kains and Godfrey.
*** Creator/LauraPost is Rosalia.
*** Creator/XantheHuynh is Sachi.
*** [[Creator/CristinaValenzuela Cristina Vee]] is Alicia.
*** Creator/{{Erika Harlacher}} ([[VideoGame/AtelierAyeshaTheAlchemistOfDusk Ayesha Altugle]]) is Sasha.
*** Creator/LucienDodge is Keita.
*** Creator/ErikKimerer is Ducker.
*** Creator/KirkThornton is Klein.
*** Creator/VicMignogna is the Salamander grunt in episode 19, the Salamander mage in episode 20, and one of the slug scientists in episode 21.
*** Amanda C. Miller ([[VideoGame/FireEmblemAwakening Sully and Cherche]]) is Yulier.
*** Akihiko Kayaba happens to be voiced by Creator/{{Marc Diraison}}, best known for his roles as [[Manga/{{Berserk}} Guts]] and [[LightNovel/FateZero Tokiomi Tohsaka]]. Interestingly enough, his role was miscredited to Creator/CrispinFreeman due to the misinformation from the Wiki/{{Wikipedia}} ''and'' Website/AnimeNewsNetwork, possibly due to Kayaba "sounding" like him early on. [[note]][[https://twitter.com/CrispinFreeman/status/360139887279751168 He also mentioned that SAO was dubbed using non-union actors]] and since Crispin [[UsefulNotes/UnionsInHollywood is a member of the SAG and doesn't have Financial Core status]], this cannot be so.[[/note]]
*** According to Danielle [=McRae=], the voice actress of Karma and Painwheel, she will be voicing a few characters in this anime [[note]]Also stated that this will be her first anime role.[[/note]]
* NamesTheSame: Creator/YoshitsuguMatsuoka has voiced another character named [[HanaSakuIroha Kirito]] before.
** Episodes 5 and 6 feature a character named [[Franchise/{{Transformers}} Grimlock]].
** [[Manga/KOn This is not the first time]] that Creator/StephanieSheh voiced a Yui-named character.
* OlderThanTheyThink: Most people starting LightNovel/SwordArtOnline will think the series was inspired by the Franchise/DotHack series when in reality both series started around the same time in 2002. Sword Art Online was originally meant as an entry for the Dengeki Novel Prize contest but Reki Kawahara didn't submit it because it exceeded the page limit so he published it as a webnovel under the pseudonym Fumio Kunori. It was only after the popularity of his second novel series ''LightNovel/AccelWorld'' that his publishers convinced him to release ''Sword Art Online'' as an light novel in 2009.
* NoExportForYou: Averted with most of its properties, except for the first [=SAO=] game though it has been included in the second game released overseas and the social network game.
* PlayingAgainstType: Oh hey, it's Creator/ToddHaberkorn! Is he voicing TheHero? ...No. Well, maybe he's voicing the comic relief? ...No, that'd be wrong too. Wait, you mean he's voicing the BastardBoyfriend of Asuna?
* RelationshipVoiceActor: [[Creator/ToshiyukiToyonaga Keita]], [[SaoriHayami Sachi]] and [[Creator/TakuyaEguchi Ducker]] are [[MobileSuitGundamAGE young Flit Asuno, Yurin, and Asemu]].
** [[TsubasaYonaga Sasamaru]] and [[KenjiAkabane Tetsuo]] are [[Anime/CardfightVanguard Aichi Sendou and Kenji Mitsusada]]
** Kirito and [[HarukaTomatsu Asuna]] are [[LightNovel/BodaciousSpacePirates Sandaime and Gruier Serenity]].
** The English Dub has a ''lot'' of this:
*** [[Creator/CassandraLee Leafa]], [[Creator/ChristineMarieCabanos Silica]], [[KyleHebert Kains and Godfrey]], [[Creator/SarahWilliams Lisbeth]], [[Creator/CristinaValenzuela Alicia]], [[Creator/LaurenLanda Sakuya]], and [[Creator/MarianneMiller Recon]] as [[Anime/PuellaMagiMadokaMagica Kyubey, Madoka, Tomohisa, Sayaka, Homura, Kyoko, and Kyousuke]], respectively.
*** [[Creator/CassandraLee Leafa]], [[Creator/ChristineMarieCabanos Silica]], [[Creator/StephanieSheh Yui]], [[Creator/XantheHuynh Sachi]], and [[Creator/AmandaCelineMiller Yulier]] were [[Manga/KOn Ritsu Tainaka, Azusa "Azunyan" Nakano, Yui Hirasawa, Ui Hirasawa, and Satoshi Tainaka and Megumi Sokabe]], respectively. [[Creator/TonyOliver Sigurd]], [[Creator/ErikaHarlacher Sasha]], and [[Creator/ErikKimerer Ducker]] also had a few bit parts here and there.
*** [[Creator/BrycePapenbrook Kirito]], [[Creator/KirkThornton Klein]], [[Creator/ChristineMarieCabanos Silica]], [[Creator/KyleHebert Kains]], [[Creator/PatrickSeitz Agil]], [[Creator/StephanieSheh Yui]], [[Creator/CassandraLee Leafa]], [[Creator/AmandaCelineMiller Yulier]], [[Creator/DerekStephenPrince Kibaou]], and [[Creator/CheramiLeigh Asuna]] are also [[Manga/BlueExorcist Rin Okumura, Shiro Fujimoto, Shiemi Moriyama, Ryuuji "Bon" Suguro, Igor Neuhaus, Kuro, Noriko Paku, Yoshikuni, Reiji Shiratori, and Yuri Frederick Egin]], respectively.
*** [[Creator/BrycePapenbrook Kirito]], [[Creator/PatrickSeitz Agil]], [[Creator/CassandraLee Leafa]], [[KyleHebert Godfrey]] and [[Creator/StephanieSheh Yui]] are [[LightNovel/{{Durarara}} Masaomi Kida, Simon Brezhnev, Saki Mikajima, Horada and Miria Harvent]] respectively.
*** [[Creator/CassandraLee Leafa]], [[KyleHebert Kains]], [[Creator/BrycePapenbrook Kirito]], [[Creator/ErikKimerer Ducker]], [[Creator/SarahWilliams Lizbeth]], [[KaijiTang Schmidt]] and [[Creator/ErikaHarlacher Sasha]] are [[NurarihyonNoMago Yuki-Onna, Aotabo, Kappa, Inugami, Sannokuchi, Akifusa Kekain and Wakana Nura]] respectively.
*** [[Creator/ErikKimerer Ducker]], [[Creator/StephanieSheh Yui]], [[Creator/LucienDodge Keita]], [[Creator/SarahWilliams Lisbeth]], and [[Creator/AmandaCelineMiller Yulier]] are [[LightNovel/AccelWorld Haruyuki, Chiyuri, Takumu, Yuniko, and Megumi]]. If you listen carefully, you can catch [[Creator/KyleHebert Kains and Godfrey]], [[Creator/KaijiTang Schmidt]], Yolko (Natalie Hoover), Diabel (Sean Chiplock) and [[Creator/ErikaHarlacher Sasha]] providing additional voices as well. Bonus points for being based on another Reki Kawahara work, too.
*** [[Creator/CheramiLeigh Asuna]], [[Creator/ChristineMarieCabanos Silica]], [[Creator/StephanieSheh Yui]], [[Creator/SarahWilliams Lisbeth]], [[Creator/CassandraLee Leafa]], [[Creator/XantheHuynh Sachi]], [[Creator/KyleHebert Kains and Godfrey]], [[Creator/PatrickSeitz Agil]] and [[Creator/LauraPost Rosalia]] were once [[{{Neptunia}} Plutia/ Iris Heart, Nepgear, Abnes, Uni, Gust, Falcom, CFW Judge The Hard, Copypaste and Arfoire]].
*** [[Creator/CheramiLeigh Asuna]] and [[Creator/PatrickSeitz Agil]] were once [[Webcomic/AxisPowersHetalia Liechtenstein and Germany]].
*** Terrifyingly enough, [[Creator/ToddHaberkorn Sugou]] and [[Creator/CheramiLeigh Asuna]] are also [[Manga/FairyTail Natsu and Lucy]], [[Manga/SgtFrog Keroro and Natsumi]], and [[Manga/SoulEater Kid and Patty]].
*** [[Creator/ChristineMarieCabanos Silica]], [[Creator/CristinaValenzuela Alicia]], [[Creator/SarahWilliams Lisbeth]], [[Creator/LauraPost Rosalia]], [[Creator/LaurenLanda Sakuya]], and [[Creator/KaijiTang Schmidt]] are [[VideoGame/{{Skullgirls}} Filia, Cerebella, Peacock, Valentine, Squigly, and Republican Double]], respectively. In addition, Schmidt, Sasamaru (Bobby Thong), and [[Creator/ErikKimerer Ducker]] also spend time moonlighting as members of the Black Egrets.
*** [[Creator/BrycePapenbrook Kirito]], [[Creator/ErikaHarlacher Sasha]], [[Creator/CassandraLee Leafa]], [[Creator/AmandaCelineMiller Yulier]], Diabel (Sean Chiplock), [[Creator/LucienDodge Keita]], and [[Creator/KaijiTang Schmidt]] are also [[VisualNovel/{{Danganronpa}} Makoto Naegi, Kyoko Kirigiri, Aoi Asahina, Toko Fukawa and Junko Enoshima, Kiyotaka Ishimaru, Hifumi Yamada, and Yasuhiro Hagakure]], respectively.
*** [[Creator/BrycePapenbrook Kirito]], [[Creator/ChristineMarieCabanos Silica]], [[Creator/KyleHebert Kains and Godfrey]], [[Creator/DerekStephenPrince Kibaou]], and Yolko (Natalie Hoover) are also [[VisualNovel/SuperDanganRonpa2 Nagito Komaeda, Chiaki Nanami, Kazuichi Souda, Fuyuhiko Kuzuryuu, and Sonia Nevermind]], respectively.
*** [[Creator/BrycePapenbrook Kirito]], [[Creator/CassandraLee Leafa]], [[Creator/LaurenLanda Sakuya]], and [[Creator/KaijiTang Schmidt]] are also [[VideoGame/TalesOfGraces Asbel Lhant, Sophie, Little Queen, and Raymond Oswell]], respectively.
* WhatCouldHaveBeen: According to Danielle [=McRae=], [[https://www.facebook.com/permalink.php?story_fbid=577081022331865&id=257517404288230 she originally was going to voice]] Yulier, but that role was given to Amanda C. Miller instead.
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