When scientific experts criticize “Gravity” for failing to display an academic-level understanding of the laws of nature, they are missing the point. Nobody goes to “Gravity” for a physics lesson; they go to be entertained. But there are times when a fact-check of a film can provide necessary context and, especially if the film is based on true events, illuminate not just how a narrative deviates from the truth but why it does. At their best, expert reviews can even illuminate deeper truths, like how reality is an often unintended casualty of pop culture. Since mainstream movies only show us what we want to be true—almost by definition, a film that sells tens of millions of tickets does not challenge any widely-held perspectives—movie fact-checkers can show why a certain film felt the need to diverge from reality to tell a satisfying story.