So I had 157 firsts but then I got another first on one round and it didn't count. There was 22 mice in the room by then.Then the Reapers map came and I got first and it counted.Help?

firsts shouldn't count in the grim reaper map though..

Both Grim Reaper's mansion and Vampire (flying for candies) maps don't count firsts, but many people do think that...
Only the two first Halloween 2012 maps do count ;)