I'll log all the known bugs in this thread. If you find a bug that isn't on the list you can report it here.

PIXI related:

-The creating-eating block if screen 0F of the cave doesn't load
-Levels crash after 84 sprite even with SA-1

Sprites on platforms related:

-Mario can stand past the edges of a line-guided platform. Image.
-(Minor) Sprites that turn away from the edges of platforms and floors will fall from fast moving platforms, including the rotating gray platforms and the flying Question Blocks.
-(Minor) When Small Mario hits a message box, he gets pushed on either horizontal depending on which side he hit it.
-(Minor) Leaving a carriable sprite on a moving platform may result on Mario kicking it if the platform is moving in the same direction Mario is facing.
-Cheep-cheeps don't interact with solid blocks
-(Minor) A flying rock platform can push a line-guided sprite out of the line-guide.
-Boo blocks have weird interactions with Mario.

Other:

In the SMB3 level, aftear defeating the boss, part of the clear text is hidden by the layer 1.