Well, it's just a quick shot in a very busy scene; it's easy to miss. But right as Butch pauses, halfway out the pawnshop door, we see behind him a confederate flag on the wall hanging right next to the American flag.
Is it just a coincidence that, in the scene where we see the confederate flag, we have a white man contemplating the rape of a helplessly bound black man being carried out by two men whose accents sound distinctly southern? It sounds like a bit of a stretch to say Butch's rescue of Marsellus is an allegory for racial injustice but, then again, the confederate flag probably isn't just chillin' there for no good reason. Tarantino doesn't do that. We'll leave the interpreting up to you.