* 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?"''
* TheCastShowoff: Takeru Satoh portrays 1 character who's gained a total of 7 different possessed personalities (some of them by force), sings in every version of Double-Action (except Gaoh Form, Coffee Form, Climax Form, and Strike Form), his own solo song, Real-Action, and, thanks to Ryutaros, has an excuse to demonstrate his breakdancing skills.
* 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.
* {{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 movie Riders use reworked Den-O suits; taking it a step further, Gaoh's suit was used to create Yuki, which is the reason [[Series/KamenRiderDecade Diend Complete Form]] doesn't have a Den-O representative[[note]]The producers wanted to use Gaoh, but couldn't because they didn't have the suit anymore, so they decided to just leave Den-O unrepresented.[[/note]]
** 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.
** A few of the Imagin were reworked from others; for example, the Owl Imagin from Ryutaros' character focus episodes was turned into the Bluebird Imagin that appears late in the series. More obvious examples include the Leo and Albinoleo Imagin (both of whom are Kai's subordinates) and their Leo Soldiers (reworked from [[Series/KamenRiderKabuto ZECTroopers]]).
* RomanceOnTheSet: Takeru Sato (Ryotaro) and Rina Akiyama (Naomi) dated for a while in 2008.
* StarMakingRole: Of all the ''Kamen Rider'' main actors, Takeru Satoh is the actor with the most abundant post-''Rider'' career.
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