Above: The barber crashes through a skylight and is eventually apprehended by the stormtroopers. Watch the stunt here.
Chaplin actually fell through the skylight in this scene--a 15-foot fall. The "glass" was made from boiled sugar & water. He filmed the stunt in one take.
Below: Production sketches show how the fall was done. These sketches, by art director Russ Spencer, appeared in the December 1940 issue of Photoplay.