So I beat SM3DW, some things:
The in-game timer is off. It's ~1.35x fast (makes clearing Flower-12 tough). Happens with both interpreter and dynarec.
At least 2 levels are unbeatable due to unimplemented mic (needed to blow fans in 1-Toad and 2-2).
At least 3 switchboards don't work (2 in 3-7...