Yeah, I think I may've had a bit of a brain fade since I'd already used the slot to get the machine started and then open up Syria. I wound up playing during several different sessions and I thought "Okay, the game is being nice and having you use everything once." Or maybe I was thinking more on the lines of "put USB port A in slot B." I guess I never considered the slot could be like a mail slot.
So after I took a break, came back and got the Damascus Steel, I went through the process of elimination of what still needed use, and I crossed the slot off. Leaving me with ... nothing! Oops.