Not sure if it's an actual "Bug," but it is possible to visit the Air Magic Expert, who resides above the bank in town, without casting "Fly."
If you maneuver the party into JUST the right position between the bank and the stable, the ceiling disappears...and you can then click on the door.
That is one "Bug" that I often use to my advantage; it saves me a lot of nonsense.
Then there's the "Door bug," where the door doesn't quite fit the door frame. This is especially true in the Warlord's Fortress in Silver Cove; you can cast RING OF FIRE to awaken the monsters on the other side, then stand JUST out of reach, and as they run back and forth across the gap in the door, hack away at them. It's fun!