It first starts off when one of the mothers takes her daughter to the doctor because her tongue has turned 'Red'. If this town has never had anything in color before, how can the townspeople distinguish whether these things are called colors, and what type of colors they are? It's something to think about, don't you think?
If you watch the movie again, while the ladies are playing gin (I think), one lady says something like "It was red...not just red, but REAL red." I think this just fits with the satire of the whole movie. For instance, Bud's girlfriend gets scared by the rain. He tells her "Its just rain" and then she says "real rain?" She hasn't ever seen it before, but she knows about it.