If I was teaching in a classroom, I think I might engage my students in this question: what was true, and what was not, in that movie you saw last weekend? They could be assigned a recent film (Argo; Lincoln, The Social Network, The Kings Speech, The Patriot, Titanic, JFK, etc.etc.etc.) and be asked to research how the filmmakers stayed faithful to, or swayed from, the truth. There's no shortage of fact-checkers it seems: the net is full of detectives out there identifying distortions and other errors of fact.
Here's an essay from The Hollywood Reporter that might be worth holding onto and/or sharing.
Since THR is read, primarily by the industry, part of its take here is on whether the truthfulness(or lack thereof) hurts box office and whether that even matters. (let's not forget the media literacy concept: media are businesses)
Excerpt: "But today we live in the age of Google, when a quick fact-check is just an Internet search away. And so movies -- especially movies running the gantlet of the Oscar-vetting process -- can't get away as easily with playing fast and loose with the truth."