Trivia: When we see the "regulators" riding over the hill on the way to kill Django and Schultz, if you look carefully at the right-center portion of screen, you can see one of the stuntmen fall off his horse and the horse continues to run down the hill without him. To make matters even worse, it appears the stuntman rolls right in front of another horse and gets trampled. (00:41:00)
Trivia: In the scene at the dinner table where Leonardo DiCaprio slams his hands on the glass on the table, he actually cut his hand - it wasn't scripted. (01:59:55)
Answer: Django and Schultz killed some of Big Daddy's farmhands, and he wasn't going to let a freed slave kill some of his workers. Schultz knew Big Daddy would come after them for what they did. Plus Django would never let go of a chance to kill a slave owner who was trying to kill him.