If Jack still had an immunity pass
 

Would he have been able to use it or still be in the tag?

He'd probably have been able to use it, tagged someone else who was free to tag him right back. It'd be great if the house got rid of all three immunity passes and he was still up. I'd say he'd be livid.

He would still have been able to use it, pointless giving him it otherwise.

I bet Jack has to major regrets in the house now,using one of his passes to save Cristian and the other in not taking the car,especially if he now secretly or openlyly believes Marc could be the winner of BB this year too