Christian Bale is known for being a serious actor, which is certainly true enough in the sense that he obviously takes his responsibilities extremely seriously and is clearly one of the best actors in the world right now as a result. However, he has also developed the reputation for being too serious when the cameras arent rolling, in part because of the well-documented, expletive-filled rant on the set of Terminator Salvation a few years back, but also because of his tendency to stay in character. Bale famously maintained his Bruce Wayne accent throughout his press commitments for Batman Begins because he wanted to avoid confusing viewers who were unfamiliar with his work and also because he feared besmirching an American icon. But Bale is nothing like as serious as some might think when Amy Adams was asked whether she found anything surprising about her American Hustle co-star, she replied, Hes funny. Really, really funny. As for his tendency to stay in character on set, well, theres a reason for that:
I tend to stay in character between scenes to be rather serious on set, but heres why, and I think people will find it surprising. Im one of the worst corpses on a movie set, which means you cant keep a straight face. You start to get the giggles and you cant stop. I never want to step out of a scene and be objective, because as soon as I do, I find it hilarious.
I watch movies and I watch sport. I also watch movies about sport, and if there were a sport about movies I'd watch that too. The internet was the closest thing I could find.