We have seen a few "documentary" styled presentations, by the Discovery and History Channels that we have been told are on cable tv, claiming to present historical facts about Christianity. They were very inaccurate and came to a conclusion that was slanted to be anti-religion.
There are many so called films about the "faith" that are presented as truth, but it is always important to find out who the film makers are and what their perspective or motive is.
It has been our experience that you can really trust EWTN as far as simple Catholic documentaries and presentations, about the saints etc. And the other major Christian networks have reliable historical presentations about the Bible and archeology, (as long as there is no political motive behind it).
I know very little about these things, but someone once said, when it comes to history books and their accuracy, etc., it depends on who wrote the book. So it is always good to do a little research and find out if what was presented is indeed an accurate account.
But I have noticed that if I listen very carefully that is with my heart, truth carries its own anointing, and along with that, peace.
Something that is being falsely represented usually creates a sense of anxiety and doesn't ring true.