I played for a good while and couldn't find anyone wearing one
I saw quite a few people wearing them. I wasn't good enough to dominate any of them, though a number of them dominated me.
The event messages said some people got the hat, but didn't say they'd gotten the achievement, so it might drop randomly as well as earned.
So if I don't play it this weekend, I won't be able to see it? Aw...
Honestly, I have no idea. It could be the map will continue to have all the themed stuff even after the event, maybe it won't.
It's a lot of fun. I'm going to be playing a lot of TF2 this weekend, I can tell.
Small health packs have been turned into candy bars, and medium health are ??? something.
There are exploding pumpkins littered around, that periodically respawn.
The ghost wanders around scaring players silly. You can move, but you can't do anything else. (Collecting 20 pumpkins gives a paper bag mask.)
Players drop pumpkins full of candy when they die, and grabbing one of these gives a short crit boost.
I don't know if this happens on other maps, or just on the KOTH_Harvest_Event map.