According to Vulture, The Hunger Games: Catching Fire (which, for the record, is based on a series of YA books) just "barely" avoided catching an R rating from the MPAA. Not because Katniss suddenly picked up an affinity for cursing, or any raunchy sex scenes between Effie Trinket and Caesar Flickerman, though—but instead because of some intense violence, which was taken out in editing last minute. As producer Nina Jacobson told Vulture at the NYC premiere of the film:
"We had one shot where one of our tributes is killed at the cornucopia, and we had to move where the arrow hit him, from one part to another part...it used to hit him in the face, and now it hits him in the chest. But it was really pretty minor, all things considered," she explained.
They weren't too broken up about it, either—as Jacobson went on to explain, she and director Francis Lawrence are more interested in the "consequences of violence than the expression of violence...we're never really dwelling on the gore of the games. It's much more about the emotional effect."
Someone should introduce them to George R. R. Martin.