collegiate-deviance:

Leonardo DiCaprio cut his hand while the cameras were rolling on the set of Django Unchained and kept moving through the scene, never breaking character, and  his real-life bloodied hand made it into the final version of the film. During one take of that scene, DiCaprio unintentionally slammed his hand into glass, creating a gash that later required stitches. But that didn’t stop him from doing his job. As his hand bled quite visibly, DiCaprio kept going, even using the hand as a new dramatic prop. At one point he smears his bloodied hand over Broomhilda’s face in an act of evil dominance. And Broomhilda (Kerry Washington) looks horrified as he does it. (Perhaps Washington wasn’t acting!) And that was the take that director Quentin Tarantino kept in the film. (Source)