I just remembered a funny bug when buying a (escaped) hero in a captured castle ... This hero does not belong to me, although I can still buy him an army. On the next turn, he attacks me with my own army. Now I will even make a video :)
hehe, yeah, I found this bug while playtesting with my brother in the weekend and we had a good laugh about it. Betrayal at the tavern - tale as old as time