Author Existence Failure: This show was being concieved by Eiji Tsuburaya on his deathbed, and his son brought the idea to fruition.
Prop Recycling: Detton was made from the deteriorated Telesdon suit from "Ultraman".
Kingsaurus 3's head was remade into Femigon's.
Ghostron was loosely modified from Earthtron.
Alien Baltan, Jr. was remade from the "Ultra Fight" Baltan suit.
What Could Have Been: Originally, Eiji wanted the show to be a revival of the original, with the original Ultraman returning to Earth and Hayata reclaiming his identity as Ultraman, however Hajime scrapped these plans. It made more sense from a merchandising standpoint to create a new hero.
Black King was intended to be the brother of Red King and would have used the same suit.