On my first archery deer the nock came off. I got a complete pass through at 12 yards and the arrow stuck in the dirt right where the deer was standing, but the nock was never found.
If the arrow was sticking out of your deer, the nock could have struck a tree and fallen out.
Good luck on finding the deer. Any deer that wasn't recovered in time to save the meat, I would count it as lost regardless of whether the antlers were recovered. It happens every once in a while, no shame in it as long as you took an ethical shot.
Good luck.