* AllStarCast: One of the few things known in advance despite the mystery during the promotional stage was that the voices would be done by a lot of well-known voice actors. To name a few, Creator/DaisukeNamikawa, Creator/DaisukeOno, Creator/JunFukuyama, Creator/MamoruMiyano, Creator/YuiHorie, YuukiKaji, Creator/MiyukiSawashiro, Creator/TetsuyaKakihara, Creator/TakahiroSakurai, and Creator/TomokazuSugita.
** The English dub (in line with Creator/{{Studiopolis}}' tendency to cast well-known anime voice actors) is like this as well, featuring Creator/SamRiegel, Creator/MatthewMercer, Creator/BenDiskin, Creator/PatrickSeitz, Creator/ToddHaberkorn, Creator/TaraPlatt, Creator/KeithSilverstein, Creator/ColleenOShaughnessey, Creator/StephanieSheh, and Creator/JohnnyYongBosch.
* IKnewIt:
** Many people on forums and WMG correctly guessed that [[spoiler:Weismann's spirit is in Shiro.]] Doesn't make it any less epic of a plot twist though.
** Many people guessed that [[spoiler:Mikoto was going to be KilledOffForReal]] from early on in the series.
* NamesTheSame: Mikoto Suoh shares both his first and last name with an entirely unrelated girl from ''Manga/SchoolRumble''. Technically speaking, the one from ''K'' typically has his last name romanized as "Suoh" while the one from ''School Rumble'' has hers romanized as "Suou", [[SpellMyNameWithAnS but it's still the same exact name]]; "ou" and "oh" are two different but equally valid ways to romanize a long "o" sound in Japanese.
* PlayingAgainstType: Creator/LucienDodge, best known for his young teenager roles like [[LightNovel/AccelWorld Takumu]], [[LightNovel/SwordArtOnline Keita]], [[LightNovel/FateZero Waver]], and [[Anime/{{Pokemon}} Chili]], voices Adolf K. Weismann; a 60+ year old ''villain'' (although to be fair, [[OlderThanTheyLook he doesn't look like he's 60 years old]] and is immortal). [[spoiler: This could be a subversion, as the said Adolf K. Weismann is actually the Colorless King, the ''real'' villain of the show, controlling Weismann's body and the real Adolf K. Weismann have been body-swapped into a 17-year-old Japanese schoolboy.]]
** [[spoiler: ActingForTwo / ActorSwap: Shiro and Weismann's voice actors share the roles of the Silver and Colorless kings - the voice stays with the body and their characters are drastically different. One wonders what they did to coordinate, to pull it off so epically.]]
** PigeonholedVoiceActor: On the other hand, we have Creator/KeithSilverstein voicing a [[TheStoic stoic]] character; Creator/TaraPlatt as a stern, serious, adult woman; Creator/SamRiegel as an OrdinaryHighSchoolStudent ([[spoiler:[[SubvertedTrope NOT!]]]]), Creator/MatthewMercer as a {{Badass}} character, Creator/StephanieSheh as a GenkiGirl, and Creator/CarrieSavage as a [[{{Moe}} cute]] highschool girl
*** At the same time, Kuroh is sort of a spoof on the types of characters Creator/DaisukeOno and Creator/MatthewMercer tend to play, what with his naive side and [[TheKnightsWhoSaySquee the whole tape recorder thing]]. Likewise, Shiro isn't your average high school student character, even when he is, and Neko isn't your average GenkiGirl. All of them actually require a lot of subtlety to keep them from becoming irritating, and their voice actors manage it.
* ShoutOut: A certain pair of Mikoto's Clansmen might find the end of the first season familiar (This is a MUCH bigger spoiler for the thing it's referencing, so to prevent accidental looks, the "certain Clansmen" are [[spoiler: Yata and Kusanagi]]).
** In detail: [[spoiler: The King is killed by someone who was something of an [[FoeRomanticSubtext enemy ''and'' love]] to them, who doesn't want to have to do it. The pose is the same. His last words are heard by a young girl with some degree of psychic ability, who succeeds him. The SwordOfDamocles is no longer a threat. The King's FieryRedhead subordinate didn't realize what was going on until it was too late. The King's closest supporter and companion has accepted this fate and says the final words of the series thanking the King. Top with brilliant, TearJerker music.]]
*** And after that, he keeps showing up - [[spoiler: whether it's their imagination/dream or his ghost is up to the viewer.]]
*** If you really must know, the series is [[spoiler: Code Geass: Lelouch of the Rebellion]], but don't spoil yourself with this!