* AuthorExistenceFailure: ShotaroIshinomori died while writing the concepts for this series.
* FakeNationality: Jean's actor, Serugiu Vasilov, is actually from Romania, while his character is meant to be French.
* HeyItsThatGuy: Yusuke's teacher [[ActorAllusion was previously a university professor in]] ''KamenRiderBlack''.
* InferredHolocaust: Kuuga's Rising Mighty Kick causes a gigantic explosion, which at one point happens in a heavily urban area. [[spoiler:This is the point in which the show begins to show that Kuuga becoming even more powerful isn't a good idea...]] While no one is actually killed in the blast due to Godai informing Ichijo ahead of time that his kick might be too powerful, the property damage leads the police to begin doubting No.4's status as an ally.
* WhatCouldHaveBeen: There was supposed to be a [[TheMovie theatrical film]] set after the events of the TV series, but the project languished in {{development hell}} when the writers couldn't come up with a satisfactory way to continue the story and the production was eventually canceled in 2006.