Currently, Giant Serpents can open doors, which they shouldn't be able to do. Additionally, they seem to be able to track players from a great distance. I.E., if you aggro one at a corner of the Jhelom bull field, paralyze it, then run to the hut in the opposite corner inside the hut, they will track you down immediately once un-paralyzed, even though you're well out of their line of sight and 20-30 tiles away.
They shouldn't, you're correct, thanks. The current AI for most creatures will allow a creature to follow any current or recent aggressors to a substantial distance. This may change in the future as we review the AI behavior in general, however until then the use of invisibility or the hiding skill will break a creatures focus & stop them from following you any further.
garrion attacked an eagle in town and invised, it still can after him several times so he had to kill it
Some mobs, like wisps if I recall correctly, will continue to aggro you after you've died from them and ressed as far as I recall. Haven't tested in a while but I know I got res-killed by a wisp like 10 times many moons ago. Personally, I like the long range tracking on mobs. It keeps things challenging/interesting much more than the ability for magic mobs to gheal themselves to full health in 20s.