If you complete the game, selecting Quit from the menu after the ending will take you back to the SMAS+SMW title screen instead of the SMB3 title screen.
SMW physics-related bugs:
* In the SMB1/SMBLL water levels, you can swim above the surface of the water by holding up and pressing B repeatedly.
* If you get SMB1 8-4, SMBLL 8-4 or D-4, you will not be able to proceed if you beat the level. Mario's automatic movements with the altered physics will cause him to fall in the lava pit, lose a life and take you back to the map.
Suggestions:
* Skip the level preview screens for SMB1 and SMBLL. They're the only ones not consistent with the other games. SMB2U's world theme previews do not show.
Viewing post in Super Mario All-Stars Crossgame Randomizer comments
I was wrong to say that the SMW physics always prevent you from proceeding, but it seems to occur more often than it doesn't for me. Unknown factors seem to affect where Mario will stop on the platform. You'll first notice something is wrong if Mario stops in the air one tile to the right of where the higher ledge of the platform ends. He will run and fall off the lower ledge before he can jump. Sometimes the score tally will start before the death is detected and the cutscene will proceed as normal with Mario under the lava. In other cases, I've seen Mario stop on the very edge of the upper ledge or gravity take effect before he stops. The cutscene will proceeded as normal in both of these.
Seed: fa963; SMB1 World 8-4 replaces World 6-Fortress 1. I had to make a savestate and resume on a version of the hack without the SMW physics.
I did recreate the 8-4 death bug while testing on real hardware and will resolve it soon.
I actually originally did skip the SMB1/LL level previews while building the first version, but it caused some weird level loading issues that I didn't feel like chasing down so I just restored it. I actually kind of like the level previews and the only reason they're not in SMB2U is because it's part of the character select screen, but I guess if it annoys people I could work to remove it or hide it.