Der Test (1964)

Two boys try out a home-made flying machine in their children's room at night. For another test, a rat that the boys keep as a pet is thrown out of the window with a small rocket. After this has also worked, the first boy stands on the windowsill ready to jump into the yard. At this moment, a man suddenly flies into the children's room from outside through the window, introducing himself as an inhabitant of Mars.