* ActingForTwo: Ryosuke Miura, of course, plays both Ankh and Shingo Izumi. [[spoiler:Both characters are only active for a very brief period in #42 after Ankh absorbs Lost Ankh and regains his full Greeed body.]]
** Marie Kai plays both Chiyoko and [[spoiler:Dr. Maki's sister Hitomi in [[PosthumousCharacter flashbacks]].]]
** Sayako plays two {{Identical Stranger}}s in ''Movie Wars Core'', the ballerina Yoshino and [[spoiler: Nobunaga's wife Nōhime, which explains [[LoveAtFirstSight why Nobunaga wanted to have her as a consort]].]] Although [[spoiler: [[{{Yandere}} he chose to cripple her when she said no]], he had a change of heart and healed her.]]
** Like Ankh, ''The Shogun and the 21 Core Medals''[='=] BigBad Gara possesses an ordinary woman, meaning we get her actres Miki Sakai playing both roles.
* ActorAllusion: In the ''Shogun and Core Medals'' movie, we see a guy carrying a guitar who takes up the PerkyFemaleMinion's offer and get a samurai hairdo. The actor in question? Mitsuru Karahashi, who played the guitar as [[Series/KamenRiderFaiz Naoya Kaido]] ''and'' played a (fallen) samurai, [[Series/SamuraiSentaiShinkenger Juuzo.]]
** One of the Net Movies for that movie has ''Gamel of all people'' get a {{Bishonen}} makeover. Not so random if you know he was in ''Series/PrettyGuardianSailorMoon'' before this.
* DawsonCasting: Or something like it. In ''Let's Go Kamen Riders,'' IsaoSasaki plays the "Man in White," who is [[spoiler: the adult version of Naoki, separated from the Riders in the 1970s and eventually too important to history to go back and retrieve.]] However, since he was born in 1942, Sasaki was in his ''thirties'' in the year [[spoiler: 10-ish-looking Naoki was stranded in]].
* DyeingForYourArt: Ryosuke Miura (who plays Ankh) had his hair dyed and styled to play the role. His more "normal" hairstyle as Shingo Izumi is a wig.
* FanNickname: Japan has gone back to the tried and true method of numerical nicknames, giving Shintaro Goto the name "5103" (5=Go, 10=Tou, 3=San).
** Some English-speaking fans call Goto "Cakebitch". Also "Broto", in reference to a fansub group using this as a "translation" for the times when Date addresses him as "Goto-chan".
** Kougami is known as the "Cakeboss."
** [[Series/BarneyAndFriends Barney]] for the Dinosaur Greeed.
** "Lefty" for [[spoiler:Ankh]] (Lost).
** Because of the dinosaur themed Pu-To-Tyra combo, OOO has become called "Kamen Rider [[Series/BakuryuuSentaiAbaranger Abaranger]]" or "Kamen Rider [[Series/KyoryuSentaiZyuranger Zyuranger]]".
* HeyItsThatGuy: Shingo Izumi, and Ankh's "human" form in a sense, was [[Series/ChouSeiKantaiSazerX Beetle Sazer]] and the Tiger [[Series/KamenRiderFaiz Orphenoch]] in ''Series/KamenRiderDecade''.
** You might recognize Takashi Ukaji, the man who played President Kougami, as Mon-chan from the [[TwentiethCenturyBoys 20th Century Boys]] films.
** Akira Date was [[Series/TomicaHeroRescueForce R5]].
** In #17, we meet the [[Series/GogoSentaiBoukenger Chiefu]]... of a ''kendo'' club.
** And in #27 [[Series/KamenRiderRyuki Megumi]] is one of a pair of female bikers who fight the [[MonsterOfTheWeek Yummy]]... and win.
** In the ''21 Core Medals'' movie, [[spoiler: Yoshimune is played by Ken Matsudaira, who played the very same character in the 25-year JidaiGeki TV series ''Abarenbō Shōgun'']].
** IsaoSasaki makes an appearance in the ''Let's Go Kamen Rider'' film as [[spoiler: the adult version of one of the children Eiji and [[Series/KamenRiderDenO Kotaro Nogami]] befriend, who, oddly enough, is also the father of another one of those children.]]
* HeyItsThatPlace: Toku fans will probably recognize a lot of locations from other shows.
* HeyItsThatVoice:
** Creator/JojiNakata, a.k.a. [[{{Hellsing}} Alucard]] is TheNarrator for OOO and the voice of the Birth System.
** Creator/{{Yukana}}, aka [[Anime/MobileSuitZetaGundam Four Murasame]], [[Anime/CodeGeass C.C.]] and [[VideoGame/TalesOfTheAbyss Tears Grants]], voices Mezool.
** The legendary '''Akira Kushida''''s voice coming from the O Scanner.
** Kazari's voice actor was part of [[ThePrinceOfTennis certain musicals]] that lend themselves to ''Tokusatsu'' a lot.
** [[spoiler: Ankh's Body]] is voiced by Creator/MiyuIrino.
** Giru, the Dinosaur Greeed from ''Movie Wars Core'', is voiced by KenjiHamada, who voiced a certain [[Series/EngineSentaiGoOnger German shepherd...]]
* MeaningfulReleaseDate: By accident, due to the 2011 Earthquake. Episode 28, the 1000th episode of Franchise/KamenRider in total, broadcast on April 3, 2011, forty years to the day since Series/KamenRider first aired.
* NamesTheSame: Believe it or not, Billy Zane played a character called Os in the TV-movie ''[[http://en.wikipedia.org/wiki/Invincible_(2001_TV_film) Invincible]]'', itself a FollowTheLeader of Film/TheMatrix.
** The [[SpellMyNameWithAnS LaToraTah]] combo is one just a few letters away from the ''WesternAnimation/BeastWars'' ExpandedUniverse's [[http://tfwiki.net/wiki/Rartorata Rartorata]]. [=TFwiki=] even acknowledges it.
** Hiroaki Iwanaga, who plays Date/the first Kamen Rider Birth, previously played Captain ''Eiji'' Ishiguro in ''Series/TomicaHeroRescueForce''.
** Chiyoko's surname "Shiraishi" is written the same as [[Series/SamuraiSentaiShinkenger Mako's]] in kanji (lit. "white stone").
*** Similarly, Hina is written with two characters from the name [[LightNovel/HaruhiSuzumiya (Mikuru) Asahina]], another {{Moe}} with famously HiddenDepths.
** Crosses into HilariousInHindsight considering the source material - [[spoiler: Tokugawa Yoshimune]] from TheMovie goes by the incognito name Tokuda [[CrayonShinChan Shinnosuke.]][[note]]Which gets its own crossover with Series/KamenRiderFourze the year after.[[/note]] He does have the jawline to match…
* PropRecycling: The {{Homage}} to past Franchise/KamenRider in #28 involves a ZergRush of past Mooks, including the Leo Soldiers, modified [[Series/KamenRiderKabuto Zectroopers]] that actually appeared in Den-O before.
** The Dinosaur Yummy costumes from ''Movie War Core'' are re-used as [[spoiler:Dr. Maki's first]] Yummies in #32.
* ThrowItIn: Eiji and Ankh's imfamous playing with toy animals at the end of one of the net movies.
* WordOfGod: The Kougami Foundation is based on [[Series/KamenRiderFaiz Smart Brain]] as Smart Brain was the most realistic company seen in Kamen Rider with Satonaka being a toned-down version of Smart Lady. Now show of hands who wants to see Kougami be used to make the Rose Yummy or Horse Yummy?