I am watching "The Last Gangster" (1937) with Edward G. Robinson, which I DVRed from TCM back on Dec 12. There's a scene where he's being transported by train from the New York to Alcatraz. One exterior shot shows a Southern Ps-4 Pacific pulling a heavyweight train.
Hollywood movies usually featured stock footage of the AT&SF, SP or UP as they were convenient to the movie studios.
Prior to this I have never seen a Ps-4 on the move.