District 9 is a film that acknowledges and evaluates racism, proving to us that just because equality exists between most races of people on Earth, doesn't mean that humans have lost their ability or tendency to oppress whoever (or in this case, whatever) will allow it or doesn't have means to defend themselves against it. Racism also exists in the the portrayal of the Nigerians, as they are slovenly, uneducated, and ignorant "natives." As they sell them food and buy their weapons, the Nigerians basically exploit the aliens, and I would have to say that I believe it no incident that the movie was set in South Africa. What better country to use in portraying a minority rule, just as South Africa experienced many years of a white minority rule?
Also, I can't help but be reminded of the Apartheid in South Africa, Rwanda, and the Holocaust, carried out by Nazi Germany. The "resettlement" of the aliens in District 9 reminds one of a Jewish ghetto, where Jews were constantly monitored and punished (also, killed) for noncompliance. This movie just goes to show that we as humans are capable of many different types of behavior, and the movie raises questions again as to whether humans are innately good or evil. The effect of this racism allows viewers to look again at these social problems and realize that the forced separation and different treatment of "inferior" races has never worked peacefully. Ever. Why try it again and again with different races of people or even different life forms? It has never worked out and never will, and for good reason.