If you're tying yourselves into knots because the pc is going off-script, you shouldn't be throwing it back at them repeatedly and in more and more obtuse ways. You should just write what happens when Arthur doesn't extract Excalibur or Luke doesn't shut off the targeting computer.
If the box is important, then write what happens when the bad guys get it, we'll be meeting up with them by the end of the act anyway. And punish us for being thick too.
