The black guy was called a black dog in the film.

HEY HEY MAMA SAID THE WAY YOU MOOOOOOOOVE
GONNA MAKE YOU SWEAT GONNA MAKE YOU GROOOOOOVE

"Django Unchained" and "12 Years a Slave" have white characters calling black people the n-word.

I doubt there would be outcry over an unsympathetic character in a 17th century setting denouncing a black person as a "black dog."