One of our reindeers is missing

I started making this advent calendar for Art's first Christmas, so I decided to use a day at home on my own to make a real push towards finishing it in time for his second.
22 finished reindeer, one to make and one has gone missing!
I can't work out where it has gone, or whether it had a red or green coller, so I'm stuck on what colour to make the last one.

Oh well, on to the antlers.