Maybe because he thought the gun was fake and nobody informed him on the change in the script by mistake?

In Django Unchained, Leo smashes his hands on a glass cup/plate thing (I forget the exact object) and cuts his hand open. Blood everywhere, it wasn't supposed to happen.

Continues on with his lines without a stutter or wince.

Yet no Oscars?

Yeah he deserves an Oscar.

you'd be surprised how often things like this happen, in the first fight seen in fight club with tyler and edward, edwrd was only meant to do a kind of hard hit around pitt's neck area and the editing group would do the rest. however to provoke a more real reaction he punhed him as hard (and goofily) as he could in pitt's ear. pitt's reaction is real time like this one. acting isnt just about acting its about reacting

Because he's such a good actor. He really deserves all the oscars he's won.

Ye, idd, he's a bit overrated.

That was the joke my friend ;)