Who, exactly, are you clapping for? Nobody who worked on the movie is in the theatre with you. It's not like you are watching a play. And the other people in the theatre don't care if you liked the movie or not. You may as well shout, "Hey, everyone! I loved this film! Just so you know!"
I always feel like I'm missing or forgetting something and trying to rationalize everything I think I need to bring. Then there's the whole process of fitting all my stuff into my backpack that, every year, seems to get smaller and smaller.