Guides to enter these three zones using 2 different methods, one online and one offline. If you do it online then all of the mobs, including rare spawns, mining veins and herbs will be up. I really don't recommend abusing those though, you'll really show up on Blizzard's radar if you do :)

Requirements;

To do it online
Uldum- Levitate, Mind Control
Twilight Highlands- Mind Control
Hyjal- Could not do it online- I'll release a new video if I find a way

To do it offline
Uldum- Levitate
Twilight Highlands- None
Hyjal- None

Please watch the Uldum segment to see how to do it using Mindcontrol and the Hyjal segment to see how to do it offline. If you're too worried about Blizzard catching you then doing it offline will be 100% safe, since you're not really logged in, Blizzard doesn't know you're running around in there.


Music used;
Death Cab for Cutie- Summer Skin (Uldum)
Pink Floyd- The Great Gig In the Sky (Twilight Highlands)
Coldplay- The Scientist (Hyjal)

Special thanks to Manoronno for discovering the offline method!

Have fun, and remember, Blizzard might not like it if they catch you in there, assuming you used the MC method :)