I'm known to laugh at scenes in movies that are so cliched or contrived that it becomes ridiculous. I sometimes worry that I'm ruining the experience for other movie goers. I just saw the latest Hobbit movie and laughed hysterically at the scene where the orcs battle the dwarves while riding down the river in barrels. Eventually everyone in the theater caught on and started laughing too. Was it supposed to be funny or did the audience perceive it the same way I did?
Indeed yes. It supposed to be funny.
For those who also read the book knows that movies, especially the second movie according to the first one, are quite different then the books.
Making 3 movies from a book with ~350 pages is hard. Making each movie 3 hours long is harder. So the director Peter Jackson choose to fill each movie some action and many funny scenes. If you go back to the scenes where they are taken captive by the goblins in the caves, there are quite good action scene. Even you may thought if they had tried a bit harder, they would cleaned the goblins and capture the whole caves!
Barrel scene is similar to the caves except one is full of action and adrenalin while the other one is full of laughter.
The reason behind this funny or action scenes is, in my opinion, total movie time is too long according to the base book script. We are talking about a book with ~350 pages turns into movie of ~10 hours. Even hearing that makes the book fans and movie enthusiasts think about the content of the movies. Using that kind of scenes a lot, Jackson guarantees the viewer will have good time and will not get bored, or have disappointment for the big differences between the movies and the book. Filling that time is with such scenes makes the movie fans satisfied.