* ActorLeavesCharacterDies: The death of Mika is a text-book example of this, due to the Yuki Yajima's sudden departure. No one knows what happened to her, which forced the production team to get Mayumi Tanaka to do ADR in Yajima's place from episodes 7 to 10 since (at the time) her voice was similar to her. Although in January 2013 in an episode from the TBS variety show ''Arita to Matsuko no Otoko to Onna'', Takahiko Ota (Naoto Ota, Green Two) and Machiko Makino (Pink Five) said that they spotted her somewhere in Chiba, Tokyo
* TheCastShowoff:
** Jun Yabuki's actress Sumiko Tanaka is a professional stuntwoman. As such, the show goes out of its way to have her do her own stunts as often as possible, making her ''Bioman'''s undisputed badass.
** Yukari Oshima (Farrah Cat) gets to do her martial arts scenes, being trained at Gōjū-ryū Seigokan karate. At the time the show was filmed/broadcasted, Oshima was a member of the Japan Action Club (JAC), where she also got stunt action training.
* TheOtherDarrin: Ichiro Murakoshi took over for Creator/ToruOhira as the narrator.
* RealLifeWritesThePlot: Other than the infamous replacing of Mika with Jun, this is also why Messerju and Aquaiger were killed off in episode 31. Toei had already decided on upgrading the members of Gear to prevent VillainDecay and make them more mechanical, but they could not figure out a way to upgrade those Beastnoids - the most organic looking of the five - without spending substantially more money than the rest of Gear.
* ThrowItIn: An early scene in episode 16 has the suit actress for [[NiceGirl Pink Five]] [[OutOfCharacterMoment celebrate the destruction of a few Gear fighters]], before catching herself and reacting more in character to her previous outburst. Some ADR from the face actress was added in to salvage the scene and make it look intentional.
* WhatCouldHaveBeen:
** Ironically for the show which changed Sentai's SmurfettePrinciple to TwoGirlsToATeam for the first time, it was originally planned as being essentially ''[[Series/TaiyouSentaiSunVulcan Sun Vulcan]]'' ThreePlusTwo, that is having all five heroes be men!
** One concept had the protagonists be derived from fairy tales (Momotaro, Kintaro, Isshiki, Kaguya Hime). These characters would have met Bio Robo in the past before being flung to the present day and joining up with a contemporary female warrior. This was dropped for fears that the young audience would be too unfamiliar with these characters. The concept wouldn't be revisited in Sentai until [[Series/AvataroSentaiDonbrothers thirty-eight years later]].
** Before it was settled that the heroes be descendants of humans, the idea of five aliens searching for utopia was thrown around.
** The names of the five heroes were changed multiple times.
** Creator/SabanEntertainment's first attempt at adapting the ''Super Sentai'' franchise, [[http://articles.latimes.com/1986-08-12/business/fi-18776_1_haim-saban way back in 1986]], was based on ''Choudenshi Bioman'', variously titled either ''Bio-Man'' or ''Galaxy Rangers''. Haim Saban had made a pilot with the ''Bioman'' footage and original footage, but it was rejected by television networks. When he went to pitch the idea again in the 90's as ''Series/MightyMorphinPowerRangers'', he made a pilot with ''Zyuranger'' footage but kept the actor footage from the Bio-Man pilot. The names of the five main heroes and Alpha 5 (who was originally supposed to be Peebo rather than an American-original character) were left mostly the same seven years later.
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