Thanks for the comments, and for catching those bugs! I made this with the most basic resources and a custom engine, so I'm surprised it isn't more buggy, really. I'm using WebAudio to programmatically generate music and sounds, and as I understand it, that's still an "experimental" technology; I need to toy around with it some more to come up with a better, stable implementation.
As much as I want to fix bugs, I've decided to leave this particular version of the game alone: untampered after the end of the jam's time limit. I am planning to make a more full-featured game out of this, with more levels, mechanics, and music, sometime in the near future.