* CashCowFranchise: ''Den-O'' has been living on well beyond the year-long expectancy of its fellow ''Rider'' series, and doesn't look to be dying anytime soon. Lampshaded in the opening Imagin skit in ''Farewell, Den-O''.
-->''"Well, for all the talk of 'Last' and 'Farewell', it's always common practice to make a sequel, isn't it?"''
* FanNickname: Thanks to the Egyptian-looking collar and other elements, Shiro is sometimes called ''Kamen Rider Phara-Oh''.
** Because of his skull and crossbones mask and resemblance to Gaoh, he's also sometimes known as Gaoh Pirate Form.
* HeyItsThatGuy
** Most obviously, Yuto is played by Yuichi Nakamura, who was Kyosuke Kiriya in ''Series/KamenRiderHibiki''.
*** Todoroki appears as a ninja squad leader in the first movie.
** Naomi is portrayed by Rina Akiyama, who also played Mana Kazaya in ''Series/KamenRiderAgito''.
** Suzuki, the detective who helps the team in ''Climax Deka'', is played by Ryota Murai, who would go on to play [[Series/KamenRiderKuuga Yusuke Onodera/Kuuga]] in ''Series/KamenRiderDecade''. Additionally, his father is [[Series/KamenRiderBlade Hajime Aikawa/Chalice]].
** Kazuki Namioka, the Imagin contractor from episodes 3-4 went on to portray Demon Knight in ''Series/GenSeiShinJustiriser'', Shishimaru/Lion Maru in ''Series/LionMaruG'', and Lock Dealer Sid in ''Series/KamenRiderGaim''
** Yumi Saito, one of the Imagin contractors in episode 7-8, is played by Hitomi Kurihara who is also the BunnyEarsLawyer in ''Series/KamenRiderRyuki'', also the Smart Lady from ''Series/KamenRiderFaiz''.
** Saizo from the first movie is Shuichi Tadokoro from ''Series/KamenRiderKabuto''.
* HeyItsThatVoice
** Momo/Ura/Kin/Ryu = [[Anime/MobileSuitGundamWing Duo Maxwell]]/[[Manga/{{Bleach}} Gin Ichimaru]]/[[Manga/{{Naruto}} Hidan]]/[[Manga/DGrayMan Lavi]], and Deneb sounds kinda like [[Manga/{{Naruto}} Jiraiya.]] For bonus coincidence points, note that Momo's voice, Creator/ToshihikoSeki, also did the Japanese dubbing for ([[Creator/DavidTennant the tenth incarnation]] of) [[Series/DoctorWho a certain Time Lord...]]
** Koji Yusa, Urataros' seiyu also voices [[VideoGame/SonicTheHedgehog Shadow the Hedgehog.]]
** Sieg is voiced by Creator/ShinichiroMiki.
** Corrolary to the aforementioned Masaki Terasoma connection regarding Kintaros, this guy also voiced [[Series/KamenRiderBlack Shadow Moon]].
** Kohana is [[Anime/CodeGeass Empress Tianzi]].
** Negataros is voiced by Creator/HikaruMidorikawa.
** Tamaki Matsumoto has done voice overs for a few anime, including ''CodeGeass'' (as Empress Tianzi).
* {{Irony}}: The premise of the ''Cho Den-O'' trilogy: the films shine the spotlight on Zeronos, New Den-O and Diend, shoving Den-O ''himself'' in a [[OutOfFocus supporting role]] instead. (Fans did complain about ''Den-O'' becoming a CashCowFranchise, after all...)
* PropRecycling: The {{Mooks}} in ''Onigashima Warship'' are Gelnewts from ''Series/KamenRiderRyuki''; in an amusing crossover with RealLifeWritesThePlot, ''Detail of Heroes'' explains that this is entirely because the makers of ''Series/KamenRiderDragonKnight'' ordered Gelnewt costumes in bulk to use as the Mook in ''their'' series.
* RomanceOnTheSet: Takeru Sato (Ryotaro) and Rina Akiyama (Naomi) dated for a while in 2008.
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