I haven't seen it yet, but apparently last night's episode of Futurama required a mathematical formula to explain a plot element. Producer David X. Cohen is noted for leaving real mathematical statements on screen during the show and had a staff mathematician compose an original theorem for that episode:

In an APS News exclusive, Cohen reveals for the first time that in the 10th episode of the upcoming season, tentatively entitled “The Prisoner of Benda,” a theorem based on group theory was specifically written (and proven!) by staffer/PhD mathematician Ken Keeler to explain a plot twist. Cohen can’t help but chuckle at the irony: his television-writing rule is that entertainment trumps science, but in this special case, a mathematical theorem was penned for the sake of entertainment.

Link via Geekosystem | Image: Fox