The small airfields that do not have a town associated with them have a map room on base. A ground vehicle can
drive right into it and hide inside. When the enemy has all of the auto guns down and delivers the troops, a pilot, jeep, m3, or M-8 can hide in there and use their pintle gun to kill the troops. Thus, no base capture. No one is aware of them being in there.
I have not tried hiding a tank in there yet but I imagine it can be done.
You can drive in from the back side as well.
If this is an Easter Egg, then I guess we should leave it alone.