there is no charge for it. well, as long as you leave within that one hour.
you can enter the park for one hour in order to make a purchase that you might have later decided on ...
i have not used it but read about it in an older guide book.
i believe you have to put some monetary amount down , maybe the cost of a ticket???, and if you return withing the appropriate allowable time, you do not have a charge for a day park ticket.
you should contact guest services on this question of how they go about of issuing an one hour pass.