When an airborne unit is carrying a unit to island with an enemy structure the destination needs to be a tile with a land route to the structure

[ledpup]

Unit gets stuck behind the mountain:

[ledpup]

Way to solve this:

• Like water, mountains become a separate contiguous region, potentially creating separate regions within one landmass
• Mountains with roads over them will allow the region to continue over the mountain pass

[ledpup]

Solved by extending contiguous regions.