"Heston plays a martinet 'conductor' (pun here somewhere) of a USO orchestra party playing the classics to the troops. The orchestra uses for transport an incredibly authentic looking pre-war German double deck with protruding bonnet, painted in grey and with USO slogans on the mid decks and lower panels. Reminds me of pre-war Berlin deckers.
At the climax of the movie the bus provides a getaway vehicle for the surviving members of the troup, taking plenty of machine gun holes in the process. I seem to remember in the script it is mentioned that it has to accomodate 70 people!!!" (thanks Scot Fergie)