If you are in an area and attack a creature and another creature attacks, and you have the "Retreat" option on, clicking to retreat does nothing and you end up having to fight that creature.
Noticed this twice now, in the woods with the bears and armodillios, and in the dungeons with the zombies.
*edit*
Also noticed you can pick up items and then still retreat on... surely if you pick up the item on the floor you should get attacked by the waiting monsters?