My gut instinct is to just disregard movies like Prophecy or more recently, Constantine. Many of the young people I minister are drawn to those kinds of movies, which get them thinking about what is real and what is cinimatic exageration. So I use them as talking points to point them toward a more biblical understanding. Constanine places great value in relics, and as I sat alongside some guys watching it, I was able to give a running commentary on the part relics played in the Reformation and why I personally do not believe they play any part in the life of a Christian. Instead of condemning those kinds of movies, I use them as tools to set the record straight--gently and never uninvited.
"sat alongside some guys watching it, I was able to give a running commentary"
Do you get "shushed" by other people during screening? :) On the serious side, after watching "Prophecy" the first time, I did have to reference the Bible for to make sure I read the correct passage.