What happens to air and sea units that are within a city which finally razes to the ground?
In both answers, the units are not "awoken" and you could lose your units with maybe only a later inkling that something is amiss.
Air Units are destroyed.
It appears that with sea units, you are given one turn to move them out. Regardless of how many movement the unit has; you will only be able to move one move. If you end the turn with it on land, the sea unit will be destroyed. If it was an aircraft carrier, the carrier will have survived but the aircraft will have been destroyed as per the aircraft rule
Here showing 12 movement points and the move radius only shows 1 move. Here showing the units is out of moves.