When the gang responds to the barn fire, they pass a house with a screen door that a woman appears in briefly. She was not part of the cast. She was the homeowner who accidentally got in the shot. You can see her quickly leave the shot, most likely from the urging of the director.
Although different in appearance and no longer a firehouse, the Engine 43 building shown in this short is still there and occupied by several businesses. An "Our Gang" mural has been painted on the driveway wall on the southwest side of the building. In the present day Los Angeles Fire Department, Engine 43 operates out of Station 43 on Motor Avenue, about six-tenths of a mile southeast of the building in the short.