In beta and just after launch I would fall under Limsa and East Shroud a lot. I got stuck under the map in a perpetual fall in Mor Dhona once. It happened when things would lag with my old video card.

At least with Limsa you can run down to the fisher's guild, jump on the docks and get back to the playable area by running through the zone line from the opposite side, but in most cases you have to return or teleport.