If the vehicle (the Bat) took the bomb over the ocean it would have gotten blown up. But then in one of the final scenes we see Lucius having a vehicle checked and the mechanics saying that the autopilot had been fixed. The autopilot in question was the one for the vehicle Batman was using, so the one Lucius had checked would have been the same one Batman used. How did he get this vehicle back when it would have gotten blown up?