Ok, I might have a problem. The room with the moray eels is full of glitches. It's probably a problem with the emulator cuz I don't expect Nintendo to release the game in such a glitchy state. When I collect the first few coins or when I touch certain parts of the wall or even just when one of the eels gets me Wario just starts falling though the level, the scrolling screws up and pretty soon the emulator crashes. This also happens whenever I exit the treasure room so I'm not sure if I can even get that treasure at all. So I may not be able to check out the really final chapter. :/
I've been playing the main route and one change to the actual level design I noticed is in the level "Defeat Bobo". In the symmetrical room with the 2 blades that come up from the ground on either side: In the B&W version those were originally just 2 Punch enemies.
Another change is that the skulls above the boss doors and the stars above the exit doors are in the foreground for some reason so you can jump behind them.
Also, on Wario's sprites they didn't just change the shading to solid colors and removed the outlines, the original also had a lot more sprites where his shoes were a different color from his overalls.
Like here:
View attachment 1983 In the GBC version you can't see the legs here.
The wizard gooms have a very bright robe (or white, I guess).
View attachment 1987
And I love how the angler fish looks in this.
View attachment 1985
He looks like a spongebob character.
And yeah, the bee.
View attachment 1988 The new one looks much better if you ask me.