This is already known by some, yes, but far from everyone knows how to get through walls. Wall glitching has now, and has always had good potential. This has been nerfed numerous times by Blizzard, and this is one of few ways that still work. No hate please, enjoy!
Disconnect macro: /run for v=1,500 do for i = 1,GetNumFactions() do SetWatchedFactionIndex(i) end end
Step one: Find an area with a wall tight to yer' head. You can't mount here.
Step two: Start mounting up, and whilst you're mounting, spam the Disconnect macro ^.
Step three: Log in. You might get a disconnect or two, but keep trying.
Step four: When you're in, you should be mounted. Gently gently press your 'Space' bar to fly up a bit.
Step five: You're now inside the wall that blocked you from mounting! Find your way thru WoW's complex systems of walls to wherever you wanna go.