Really? Wow, then Hudson sure are assholes.
It's like that in the original. I'd argue that is a a bug, but it's one we've decided to be bug-for-bug compatable with. Theres some discussion of that a while back in the thread. We decided to leave it like that even though it's obnoxious and against the spirit of SMB, because it's the what the project is about.
At first it was suspected to be disk corruption (we've had to work around some in the only dump of SMBS we've been able to find), but after investigation, it appears not to have been. (I wonder if the Sharp X1 version is like that too. I never checked.)
I should probably mention it in the readme.
As for the music glitches, I'm not sure what's up with that. I don't think it's vine related. If anything, it may have to do with going to the coin heaven, but I don't think the means of entry would effect that. (Honestly, I do most of my testing with sound disabled to speed up the emulation. I guess I'll have to stop doing that.)
I'll go check out the level 7-4 thing. It's probably a matter of poorly placed scroll stops or something.