I am a big fan of life-close movies where things are portrayed close to what could have happened in real life. Such movies usually attempt preserving realism and follow high level of detail.
Is there a special measure of how well realism is portrayed in a movie? Or is it something that no one really cares about?
The reason for this question is actually to add an extra criterion in my search for the next movie I wish to watch.
Truth is something that can't be measured, it has to be reviewed manually according to certain criteria. So there is no automatic method to determine the realism of a movie, people need to put a lot of work into it. You can find such information about mistakes e.g. in some movie reviews or in the goofs section of IMDb (namely Anachronisms, Character errors, Factual errors, Errors in geography). This so-called free Encyclopaedia also typically has details about popular culture and its mistakes.
David McCandless did a scene-by-scene review of the truth of a few movies. He used Unknown, False, False-Ish, True-Ish, and True as categories for each scene. You can find the result here and the raw data here.
So, yes, other people do care. Still, movies are economical entertainment products and not documentaries. Determining the realism is a lot of work that in detail is not justified normally. Find a few good movie reviewers / bloggers whose style you like and who put a general emphasis on this. Reading about inaccuracies in detail before watching a movie will, of course, lead to a lot of spoilers.
Regrettably, movies must be entertaining enough to bring people in to theaters. Sometimes characters must be nicer than they really were; be combined to a more interesting, larger force than real life permitted; do things they wouldn't do to generate conflict. Without conflict there is no drama.
If there was less in life than a compelling film requires (in someone's judgement), then some gets added. To create conflict where there was none, or wouldn't reasonably be any if just fiction with 'realistic' characters, then characters must behave badly or irrationally. Then there's opposition, confrontation, conflict. Frequently this interferes with factual reporting.
