Over Hill and Under Hill

The Movie: Thorin, who is also awake, notices sand draining from the cave floor and shouts for everyone else to wake up. His warning cry is no good, however; trap doors open up the entire floor, and Thorin's Company falls several hundred feet into a large metal cage. They are immediately swarmed by hundreds of goblins, who grab the dwarves and take them all away. They somehow miss Bilbo however, leaving him alone at the cage. He draws his sword - now glowing bright blue - and attempts to follow the goblins, but a lone sentry leaps down and attacks him. After a short fight, Bilbo and the goblin fall down a great distance, into the darkness.

Yup, he's dead. Roll credits.

The Book: Bilbo has a terrible dream that a large crack had opened one of the cave walls. He awakes with a start and realizes that his dream is true - one of the cave walls had opened into a wide passage that the ponies were disappearing into. He gives a shout and wakes up the rest of the Company, just as several dozen goblins leap out of the crack, snatch up Bilbo and the dwarves, and carry them into into the dark passage. Gandalf was awoken by Bilbo's shout just in time to kill several goblins with his magic, but could not save the rest of the Company; the crack closes with a snap, with Bilbo and the dwarves on the other side of it, at the mercy of the goblins.

What difference does it make? This is a small change, really. In one telling of the story, the wall opens up, and the goblins snatch up the dwarves. In another telling of the story, the floor opens up, the dwarves fall in a cage, and then they're snatched up by goblins. The only notable difference is that this is when Gandalf is separated from the dwarves in the novel, not Rivendell.

My Opinion: On the one hand, I wasn't really in love with the way Tolkien described the opening of the wall; I could never really visualize it when I read the book. Is it some kind of magic door? Do the goblins have the ability to literally change the shape of rock? A trap door, at least, makes sense. Why Peter Jackson decided to have his characters fall several hundred feet, though, is beyond me. It takes me out of the scene, destroys immersion, and defeats any kind of suspense that the characters may be in danger. This could have been solved so easily: just have them fall less of a distance. It may be less visually impressive, but, c'mon. You need to at least pretend that dangerous things can hurt the protagonists.

Also, what the hell is up with how Bilbo escapes the goblins here? He's in as much danger as the rest of the dwarves, but somehow the goblins just.. miss him? It looks like he evades capture by standing still, then crouching down on all fours so that nobody can see him. I'm not sure that's the way vision works. I don't know why Bilbo couldn't be separated from the rest of the dwarves later, like it's done in the novel. This is not only another unnecessary change, but it's a stupid one.

I'm pretty sure this goblin has to actually go around Bilbo. 

I did like watching Bilbo handle a sword, though. He's inexperienced, and scared, and barely able to keep up with the ferocity of his opponent. Just like a hobbit ought to be, wielding a weapon for the first time in his life.