(not sure if it actually IS a bug, or just a quirk) is that I was looking at a cool embark spot I wanted, but when I went to look for the marble (used reveal), it was nowhere to be found. The granite that was above it is present, but the magma sea had apparently eaten the...
My military dwarves which were sparring a few z levels below the surface (so a good hundred above where they are in the picture) were at some point randomly teleported into the magma sea. There is no possible way to get to that location from my fort even if you could survive magma. ...