Since I've found a couple more areas where it's possible to leave the bounds of the world, I'll collect them here instead of creating a new topic for all I find. Feel free to add yours' as well.
Holding Cells: http://imgur.com/s7snGJJ
Underground Shrine: http://imgur.com/ZpNilrS
Torture rooms view 1: http://imgur.com/v29gsT4
Torture rooms view 2: http://imgur.com/g0VY9u0
(Also posted the following in its own thread):
Ship north of Braccus' Armory: http://imgur.com/WZz2dgd
Ship north of Braccus' Armory onboard: http://imgur.com/YSsPYGV