 FACT: In the beginning, when the German airplanes are bombing London  and Edmund and Peter are in the garden in front of their house, you  can see the shadows of the airplanes on the ground. This is not  possible because it is night and there is no light above the  airplanes that could cause those shadows. On the contrary,  searchlights tried to discover those airplanes from below pointing  into the sky. If there was a light above the airplanes strong enough  to create shadows, they would be much bigger (because of the  altitude) and moving much faster.