An interesting essay on (messy) fictional universes and the fans who rationalize them.
The fictional universes depicted in movies like the Star Wars or Star Trek series tend to get very complex (…) That complexity means that–inevitably–the occasional "continuity error" occurs. In normal movie parlance, a continuity error means one of those embarrassing moments when, say, the bandage on an actor moves from the right hand to the left hand between scenes due to a mistake by the makeup department. For science fiction fans, though, continuity refers to the overall logical and historical coherence of our beloved fictional universes.
If Scotty witnesses Captain Kirk's death at the beginning of Star Trek VII, it is extremely troubling to some of us–those who care, those who have intellectual integrity and the discipline of logic!–if Scotty is awakened from suspended animation approximately seventy years later in an episode of Star Trek: The Next Generation and asks whether Captain Kirk is still alive. Scotty should know that Kirk isn't! Something is wrong! It doesn't add up–yet it must! It must!
For you see, any story must have a certain amount of internal coherence if we are to achieve suspension of disbelief. And we must achieve suspension of disbelief.