I've heard that he was part of the only 3 eras of Kamen Rider that exist: Showa (as he was supposed to be part of the Showa Riders at first), Heisei (idk; I just heard that at the same time), & Neo-Heisei

since nothing has yet to be mentioned about Super Sentai, we don't even know if it's A ninja sentai let alone which one if we see a Super Sentai in this film

Regardless I won't be disappointed if Super Sentai does not feature in this film. They always have the winter VS movies to fall back to so I think it will be fine even if they don't appear. If they do somehow have them featured and make it work that is fine by me too.

Basically the coolest thing I've seen. *said as if I'm in Napoleon Dynamite*. No really, Kamen Rider 3 has to be the coolest Showa Rider aside from Black. I love it. His car is one sweet ride.

I can never keep track of these movies, but since they are rarely cannon(looking at you Decade) it doesn't bother me too much if I miss any, but that aside I really want to learn about Number Three and what his deal is

Actually most of the recent films have been canon in one way or another.

The Spring movies are never canon though since they fit nowhere in the timeline of the show. I think some of the recent films that came out during the summer and winter can be debatable like Wizard in Magic Land if they are canon or not.

I think some Rider movies try to fit themselves into canon, like KRT trying to fit itself in the middle of the Gaim Yggdrasil arc, Sengoku movie war trying to fit in between episodes 9 and 10, but a lot of them are not canon with the current shows due to contradicting details

KRT had the Super Sentai and every Rider in the movie. I believe that it's impossible for the Super Sentai and Kamen Rider can exist in the same universe due to timeline issues. Also it would be impossible for every Rider show to exist into one universe due to timeline issues as well.

Well I mean obviously if you start thinking extremely logically about toku, most of these series, movies and franchises have sketchy connections.

That said, I'd still like to think all toku (except Ultraman until they decide to add that, too.) exist in the same universe.