From what I remember, the script really ever states how the racial differences affects the outcome of the plot and story. There are no lines that talks about how Cynthia being black affects Tracey and Jessie other than when they bring up her getting promotion. But having that contrast does bring a new element to the stage when you see them fight. And like the reviewer says, it's done in a different way that I feel you wouldn't be able to notice unless you saw it in this performance