As people will start to discover this and upload content, there is bound to be worlds that will make you fall indefinitely or make it hard for you to leave the world without quitting the game (which is a bad experience overall).
With this I would like to request a additional way to leave the world that doesn't require you to open the menu.
New keyboard shortcut
Oculus and Vive trigger combo (even though it's starting to get limited on this)
Activate safe mode while falling will freeze you in the air allowing you to access the menu (disables once you start moving of course) and leave the world (thanks ScruffyRules)
This doesn't just apply to community worlds, but during development of worlds too. But I feel it will be a almost required option when CL is out (Also see comment by John H)