 In the steam engine scene where the boys are salvaging iron rails  from unused rail lines, the Norfolk & Western coal hauling steam  locomotive they see is the former Southern Railway engine #4501.  This engine is currently in use at the Tennessee Valley Railroad in  Chattanooga, Tennessee. The scenes with the locomotive were filmed  in upper Tennessee around Harriman, Oliver Springs, and Lake City  with engine #4501 pulling a string of coal hopper cars lettered in  authentic N&W livery.