Going out on a limb here....was it part of the dialogue in Von Ryans Express...as they were fleeing and were under attack from the Gerries in their Stukas...everyone would jump off the train at the start of the attack and when the stukas dissappeared (fuel low?) Sinatra ran out and shouted Back on the Train!!! Could be seen on another level eg: when something has derailed (pun intended) the smooth running of ur life (tragedy, loss ) u might after a lenght of time decide to get back on the train...it being daily life/existence .... ????
Call My Bluff!