* ActorAllusion - The Serpent Undead gets hit in the face with a ''taiyaki'' plate, leaving her face messed up; this was actually a RunningGag when the actress playing her was in the role of Wendinu in ''Series/NinpuuSentaiHurricaneger'' (but with less harmful implements like paint brushes, sooty explosions etc.).
* ContractualPurity: Around the time ''Blade'' first aired, there was a flap over the fact that Takayuki Tsubaki, who plays Kenzaki, had previously appeared in a gay porn film. For a while some fans speculated that he would get [[ChuckCunninghamSyndrome quietly shuffled out of existence]], but the fact that Tsubaki returned to play Kenzaki in the final episodes of ''Series/KamenRiderDecade'' and again for ''VideoGame/KamenRiderClimaxHeroes'' proved the fears were baseless.
** Sumiko Ozawa from ''Series/KamenRiderAgito'' makes a guest appearance, with a similar enough characterisation to make her an Expy.
** Going back even further would be Tennouji Hiroshi, who used to be Muruboshi Dan a.k.a. Series/UltraSeven.
** Hirose's father is played by Jun'ichi Haruta of ''Series/DaiSentaiGoggleFive'' and ''Series/KagakuSentaiDynaman'' fame.
* WhatCouldHaveBeen - Each of the 52 normal Undead is pretty much this. Each had the chance to be the one whose species could've ruled the Earth, the Human Undead just managed to win out. This includes lions, tigers, spiders, grasshoppers, and even some species of ''plants''. Yeah, Orchids could've ruled the world.