I wouldn't call it a bug so much as an Oversight

One of the caves you can only enter during the winter, when the water around it freezes. If you dick around too long, and don't come out of the cave until spring starts, you are stuck if you don't have enough Rune to use the teleport to home Magic.

But that isn't a bug, that's bad planning on the user's part...or is there some actual bug I am missing?

I'm pretty sure it liked to randomly delete your saves if you left it untouched for a while. But aside from that, it was kind of badly balanced, not that it matters much. Once you got access to decent ores and a good hammer you could earn all your money mining things and ignoring your farm forever, since ores sold for a lot more than farm produce, even early game.