Latin is a dead language. No one living today speaks it fluently. Yes, there are plenty of latin words & phrases still used. And yes, Catholic masses are still sometimes performed in Latin. But guess what...even priests don't speak the language! They speak the words based on rote memorization. Are you honestly saying that it should be a "slip up" because the movie makers didn't resurrect a dead language, teach it to all the actors, then subtitle it for the viewers? It's a friggin MOVIE meant for entertainment!