1) After playing for a number of turns, sound effects stop playing. This has happened to me several times.
2) Auto-resolve battles sometimes automatically move the player army to the tile where the enemy army was after the battle, even if there is still a second enemy army on the tile.
3) If you don't declare war on a minor faction the first time visiting diplomacy dialogue with the fact after it allies itself with SK, the faction may become unattackable.