Edit: Just watched your Twitch stream. Basically a head shot doesnt kill the rabbit, it just does more damage. The second loop through they're much harder to kill. I suspect better balancing might help.
It’s using proper hardware collision detection so it’s pixel accurate. With the mouse it actually drops to a hitbox of 1 pixel for the bullet so if you click a transparent part of the rabbit it won’t hit it. Also the head and body have different damage awarded and their health is a little random too.
This might have been what you were seeing. The blood splatter only appears for a brief time if you do hit and due to hardware limits there’s only ever two of those on screen at a time.











