Thank you for playing!
I've added a night counter to the end screen.
The xp bug was a bit more subtle than that. I was already cleaning up the xp on state transitions, so restarting always removed all existing orbs. However, if you killed some things and died in the same frame, the event telling it to spawn a batch of orbs stuck around until the next time you're in the game. To fix this, I added a 2 second "death sequence" after dying which should make this bug much harder to run into.
To mitigate the big guys getting stuck, I've made it so the small guys can walk through the big guys. This way, when they get stuck, they can act like walls blocking off parts of the map while still letting the small guys in.