Sorry if Repost but i didnt see anything about it in my search. It's pretty simple, thought i should share it, dont just want to be a leecher. It's not much but here it is-
Heroic Leap past invisible barriers/walls:
1) Be hovering on a flying mount above the place you want to leap.
2) Target your heroic leap past the invisible wall you want to go through.
3) Use it and it should take you beyond the wall.
*(You HAVE to be on a flying mount. It hasn't worked on ground mounts to my experience.)
Useful for exploring. You can use it in EPL to get into quel'thalas or uninstanced stratholme, getting past the gates of BT, etc, etc. Its a fun little trick to screw around with. Have fun.
*NOTE: It may not work on all invisible walls but it has worked for every wall i've used it to get past such as the ones above.