The show uses Kotaro Minami as a stunt double, with Dex dressing up in the same white outfit to blend in with the Stock Footage in some civilian fights. Most probably for budget reasons, since Saban was unable to obtain most of the monster costumes from Black RX. This explains why "Dex" is never seen in the same shot as the monster whenever he wears a different outfit other than Kotaro Minami's. At times, Kotaro's face could be seen during such fights. Keep in mind, Masked Rider is not the first show that uses this method of editing. VR Troopers, and numerous Power Rangers series have used footage of the Japanese actors as doubles for their respective American counterparts. However, the aforementioned budget forced production to use this method very often in Masked Rider. The show also uses Kamen Rider ZO and Kamen Rider J as this for suited fights as well. The close-up shots feature Dex in the RX suit, but the faraway action shots depicts him wearing a completely different outfit.
According to Ted Jan Roberts and Banner Agundez who both worked on the show, Verne Troyer of Austin Powers fame was the suit actor for Ferbus, Dex's faithful pet.
Saban's Masked Rider was adapted from three separate Kamen Rider incarnations: the TV series, "Kamen Rider Black RX," and two Kamen Rider movies, "Kamen Rider ZO" and "Kamen Rider J."
The Masked Rider Warriors are actually based off previous Kamen Rider heroes. A planned appearance from the Power Rangers got cancelled and replaced with stock footage of the Warriors.
Masked Rider Super Gold was originally called "Super Masked Rider", and it was being marketed as Dex' main form besides his default appearance, with Masked Rider Super Blue nowhere to be seen.