Sam Arbesman highlights the use of mathematics in movies, including game theory (The Dark Knight), epidemiology (zombie movies), and balance theory (Reservoir Dogs).
If you and someone else hate the same third person, but like each other, balance theory says you’re golden — all three can persist without changing their opinions. On the other hand, if all three of you despise the others, it’s an unstable triad, as well as a wildly common plot point for crime movies. While there are numerous resolutions — one person changes his preference toward another, a relationship tie is cut — another route back to stability, albeit a messy one, is the gunning down of at least one person.
Arbesman has some videos and stills on his web site from the movies mentioned in the article as well as the relevant mathematical materials.