The second bank quest (Automagic Teleport Machine) can appear before its dungeon (Shifting Passages) is unlocked.
I believe that I somehow completed the quest with the Hero's Helm as a reward without actually fulfilling its requirements, but the quest is gone from the list now so I'm not sure. I received the helm after beating Den of Danger with a Berserker, having only previously beaten that dungeon on that file with the Fighter, Thief, and Sorcerer.
One not-really-bug but more of a request I have is for the white dialogue bubbles to either not appear
right on top of the creature/sign that triggers them (maybe extend the tail so that the actual text bubble reaches near the top or bottom of the screen) or to have like an "x" or "Okay" button that can safely be clicked to dismiss the text bubble. Currently the bubbles are a little distracting and can be tricky to get rid of at times, since as far as I can tell they can only be dismissed by clicking elsewhere in the dungeon - but clicking the dungeon makes you take an action automatically, even if you click space covered by the bubble, so I'm always worried I'm going to misclick and kill myself or do something silly.
EDIT:
Weird graphical issue with the text box in Dracul's subdungeon.