It may just be me but when a land unit goes to attack an air unit, just off shore, the game spazzes. Now I now this isn't possible and apparently the game knows it too and yells at me when I try. The game sort of freezes for 10 seconds or so, maybe a bit longer and then finally lets me move my guy.
It also seems to show that you can attack the unit when it shows the path with the space on the air unit over water being black and not grey. But when you try to click and execute, it freezes. Maybe I deserve it for trying an illegal move...