I just had a funny thing happen to me. I was working on editorial changes to a short story, when I found a comment suggesting I explain who Karen Silkwood was — in connection to an in-story reference to a "Silkwood squad." It took me a minute to realize this was a generation gap between me and the editor. The editor was right, most readers more than a bit younger than me (ie, too young to remember either the original event or the Meryl Streep movie based on it) won't get it.
It's not often that I am forced to realize how much what is considered "general knowledge" shifts with time. This also points out the difference between Second World and naturalistic narrative -- in a Second World piece, I wouldn't have dropped a reference like that blind without a very good reason.