He used it to attach to his dad’s ankles to keep him from rolling along the tank tracks and getting run over during the tank scene.
Saw “A Beautiful Mind” tonight and there was the Ark in the office of one of the characters so apparently the top men were at (IIRC) Princeton.
Didn’t he also use the whip to swing from the room he was in to the room his dad was being held in at the Nazi castle?