An uncertainty about the intended rules, on which we'd like clarification, it may've been discussed before but worth bringing up anew.
When a flying unit attacks hostile territory, and then the 'retreat' action is taken, the flying unit can remain over the hostile territory. It then survives since air can now survive hovering land. This means there's a hostile unit contesting that territory, so units friendly to the controller of the territory can't move there in noncombat, though they can move there in combat and engage the flying units directly albeit without the help of other allied forces in that territory; and it also means that any units of the territory's controller (especially walls) will have to attack the flying units on their turn. This matters particularly in terms of dragons, who might attack, but not fully win the battle; then be left hanging over some hostile walls. The way the engine does things now, the walls then attack the dragons on their turn, and cannot retreat.
Is that the intended gameplay? If not, how should it be handled?