Srsly whats the point in having a portal scroll when you cant use it at 99,9999999% at the time?
Let us setup a portal, get a "Are you sure you want to leave the area? Yes/No" Message and then leave the damn expedition.
There is no use in not putting it up as it is because you can "Return to the main Menu" or "Exit" the game at any time (Did srsly nobody thought of this..?)