So the last crystal that you can look into in Cania shows mephistopheles blowing up the inn in a cutscene. Somehow, the cutscene ended and my character appeared in the inn. Mephi and his retinue were all targetted as non hostile, but I was able to attack and kill him (much more easily than at the end, since he didn't fight back). The retinue, however, wouldn't die, and there was no way out of the building. This was slightly annoying, because I had to go back and fight through all those frost giants again, but seemed worth sharing, as I can't recreate the glitch even from the same point in a different saved game (same campaign though). I saved the game in the inn though, and it does the same thing every time, goes through the cutscene, and then drops me in it.
Wierd...