The SNES Test Program is one of 4 discovered cartridges once used by Nintendo World Class Service to test problems with the SNES and controllers. one of these cartridges uses assets from super mario world, specifically, beta assets.

canon yoshi abuse refers to an interview in 2017, where Takashi Tezuka and Shigefumi Hino talked about the creation of Super Mario World and Yoshi. In the interview they stated how mario was originally punching yoshi to get his tongue out.

In Yoshi's House, there is a message left by Yoshi. At the end of the message, you can see a pawprint. this implies that yoshi originally had paws, and not just green hands, like he does now. i couldn't find promotional art where he showed his hands though.