Sooo It's been on my mind for a long time but I forgot how I discovered it and then, I just remembered. Remember Link from Game Boy (and/or Game Boy Color) games has got his own death sound? It still does the NES death sound in SMBC. The only way to hear the GB death sound is by falling in a pit. It then plays BOTH NES and GB death sound. I'm pretty sure it's not supposed to be like this. It's amusing how such a noticeable glitch hasn't been reported yet (it hasn't, right?). I guess people don't play GB Link. .__. I can't video-record anything so if someone could show that bug, that'd be nice.
I may be wrong, but I think all of the sound effects remain the same, it's just the graphics and music that change. I've often thought the sounds changing would be nice, too.
→ Well GB Link has got a bunch NES sounds but only a few GB sounds if I remember well. However, as his death sound IS here, it's definitely supposed to be played instead of the NES one.
I think I've noticed that the select sound when you choose a link skin is overlapped with the default sound as well.