Continuity mistake: At the dinner scene at Bilbo's house, just before Bofur throws the egg at Bombur's mouth, Fili is seen sitting next to Bombur. Yet as Bombur catches the egg, Ori is now sitting where Fili was sitting.
Continuity mistake: In the scene where Bilbo, now invisible, sees Gandalf and the dwarfs run past the cave and he can't join them because Gollum blocks the way. When Bilbo finally runs past Gollum and kicks him in the face and knocks him down, the very next shot shows Gollum's body lying in the opposite direction, away from the direction Bilbo kicked him. (02:19:35)
Continuity mistake: Just after Radagast has a flashback of him seeing the Necromancer, some of the white stuff on his beard disappears briefly in the shot where he inhales the stuff in Gandalf's pipe. (01:15:20)
Continuity mistake: Shortly after Bilbo finds the Elvish sword that turns blue in the presence of Orcs and Goblins there's a fight with Orcs at the entrance to the hidden valley. However, the sword doesn't glow blue. In subsequent fights with Goblins and Orcs the sword does glow blue, even when sheathed.
Continuity mistake: As Thorin is picked up by the eagle, the eagle's talons roll him towards the camera. Both of the eagle's feet are in view and you can see all the way down Thorin's body to his boots. Orcrist is nowhere on his body during this initial shot of the pickup. As soon as the shot changes (where the Oakenshield drops free) and both of the eagle's feet come back into view, Orcrist is now on Thorin's body, running over his stomach and left leg. Had it been there before, it would have been visible when the eagle rolled him towards the camera.
Continuity mistake: In the scene with the rock giants the dwarfs and Bilbo get completely soaked by the rain. Once they reach the safe rock, you see Bombur land on his back and he is totally dry. (01:48:05)
Other mistake: In this movie, Gandalf looks older than he does in his grey incarnation in Lord Of The Rings: The Fellowship Of The Ring. However, this takes place before the Lord Of The Rings trilogy, so he should look younger, or the same.
Continuity mistake: In the scene where Bilbo spares Gollum's life, Gollum turns around facing the invisible Bilbo and extends his right hand out to a rock. The far shots from in front of Gollum show his arm almost fully stretched out and his hand away. But the shots from behind Gollum show his right arm bent on the rock with his hand much closer and level with his head.
Continuity mistake: When the company are surrounded by Wargs outside the Hidden Pass, Thorin can be seen holding his sword Orcrist in one hand and an axe in the other; the shot changes and he is then holding his sword with two hands, the shot changes again and he reverts back to the original configuration. (01:20:25)
Continuity mistake: When Bofur tells Bilbo in the cave that he is homesick, Bilbo's hair suddenly gets a lot wetter. (01:50:30)
Continuity mistake: When the Ring falls out of Gollum's pocket, it lands on dry ground. When Bilbo picks up the Ring, the ground is now wet. (01:58:30)
Continuity mistake: During the song "Blunt the Knives", Balin is seen in a shot from behind sitting at the end of the dining table. He is shortly afterwards seen dancing with a broom two doorways behind. The next shot then shows him sitting down again, bouncing plates off one he is holding. (00:27:20)
Continuity mistake: When Frodo is talking to Bilbo about him being unsociable, Bilbo starts to turn to Frodo with a note to put on the gate. In the next shot, he starts to turn around again. (00:11:20)
Continuity mistake: As the dwarves, Bilbo, and Gandalf enter the troll's cave, a skeleton can be seen propped up against the entrance. In the next shot, it is gone. (01:08:55)
Continuity mistake: As the group reaches the dilapidated house that Gandalf claims belonged to a farmer, a birdhouse on a pole can be seen on the threshold. In the next shot, it is gone.
Other mistake: When giving Sting to Bilbo, Gandalf tells him it is an Elven blade and will therefore glow blue when Orcs are near. However, Glamdring and Orcrist are also stated to be Elven blades, but they do not glow blue.
Other mistake: Just after he arrives at the gathering Thorin states that he wouldn't have found Bag End had it not been for the mark Gandalf made on the door. Bilbo then claims that 'There is no mark on that door, it was painted a week ago'. However in the earlier scene where Gandalf makes the mark the paint work is cracked and weathered, more than it would have done after only a week.
Continuity mistake: When Bilbo brings the two bowls of stew for Fili and Kili there's a spoon in each of the bowls, but after Bilbo sets down the bowls one of the spoons has vanished when he picks up the bowls again in the closeup, but the spoon reappears when they run after the Mountain Trolls.
Revealing mistake: When there is a flashback of Thorin in the war, in the first few seconds, on the left of the screen, there is a man with a shield. He swings it at an ogre and you can see it misses by a good five inches, but the ogre moves his head back as if it were hit.
Continuity mistake: In the scene where Dwalin arrives, Bilbo has his hand on the door when he says "Is what down where?" His hand is by his side in the following shot. (00:16:35)
Answer: Gandalf has already convinced the dwarves Bilbo is a burglar and Bilbo realised he needs a lot to convince them otherwise. Bilbo is also intimidated by Gandlaf and confused about his claims so he is not sure how to handle the situation.
lionhead