Is there something wrong with my girlfriend?

Remember, not all people have the same sense of humor. What seems funny to you might not seem funny to them sometimes, and vice versa. I don't think there is something wrong with your girlfriend. But I don't know if I would have laughed or not because I didn't actually see the movie. Things are way more funnier when you see it for yourself. You're not always going to find the same things funny, and that's a fact. But don't get too down about it! The same scenario has happened to me and countless other people :)