How well educated is your populace and what, if anything, does it know about other cultures? Is there a race/culture your fictional world is hostile to and how did this develop? How does the media combat/inflame prejudices (and are they in the government's pocket)?
I've been listening to the Proms and enjoying some wonderful classical music. What I've found particularly interesting is the number of composers who were inspired by Shakespeare. The idea of literature feeding the world of music is a fascinating one. On your fictional worlds, and within the main world in particular, is there appreciation of other spheres of culture like this? If a more downtrodden group develops a liking for, say, some form of art that is usually the preserve of those higher above them in the pecking order, how does the world react to this?
And with so much horror in the news lately, the appreciation of different cultures is a vitally important one to get right. Without that appreciation, we run the risk of destroying each other. How can that be shown in your fiction?