In the final battle with the sheriff, the bad guy manages to injure Robin in the chin. He says "Now we are even." But when the sheriff dies, you can see that Robin's chin is not injured. He doesn't even have blood on his chin.
I guess that was Robin's little thumb to the nose to him...the guy died without really being even. (Yes, I do know this was a slip-up, excuse my bad humor)
if you look at his chin, when he is still in the window sill, but after he's killed the sheriff there is still a cut on it. it's just not bleeding, and it seems a bit smaller