basically the joke:  
THe rider there is actually Sky Rider (technically it’s Kamen Rider, but thats a different thing) but when Saban decided to adapt Masked Rider into america, they used footage from a scene that showed past riders.
 
Because the second Kamen Rider looked like the first, and Rider Man had his mouth shown they edited those two out of the line up as they named themselves. Of course, Saban didn’t take out their names when they did their script version, so they wounded up getting the names mixed up with all the riders.
 
Leading to Skyrider calling himself, “I am AMAZON!” and it’s become a meme in the toku fandom