In 2009 an Internet rumor linked David Tennant to the role of Bilbo Baggins, after he and Peter Jackson both appeared at Comic Con. Both Tennant and Jackson denied this rumor, stating he was never under consideration for the role. However, in 2010 Tennant was considered for the role of Thranduil, but had to turn it down when his then-girlfriend (later wife) Georgia Moffett unexpectedly became pregnant which prevented him from taking part in film's lengthy New Zealand shooting schedule.
Gandalf says that Bilbo's sword will glow blue when Orcs or Goblins are near. This was also meant as a clue to Gollum's origins. When Bilbo approaches the lake, his sword is blue, then flickers and goes out after Gollum kills the goblin. The sword doesn't glow in Gollum's presence, which gives the viewer the hint that Gollum is something more benign (but no less dangerous).
There are several shots scattered throughout the film where it's clearly noticeable that Robert Kazinsky is playing the role of Fili rather than Dean O'Gorman. This is especially noticeable in Trollshaw Forest, just as Thorin is beginning his song in Bag End.
How much did Peter Jackson compress the timeline in the movies?
Strangely enough, he didn't. It takes longer for Thorin and Company to reach the Lonely Mountain from Bag End in the films than it did in the book. In both, they left Bag End on a Thursday. April 27. The Company arrives at Lake-town on September 22 (Bilbo's birthday) in the book. They depart Esgaroth around October 9 and reach the Mountain at or near October 12. It takes as much as another two weeks to find the Secret Door and wait for Durin's Day. In The Desolation of Smaug, Bilbo and the Dwarves reach Lake-town on October 25 and Erebor on October 27 (Durin's Day in the film).
If Aragorn were to appear in 'The Hobbit', how old would he be?
Does Peter Jackson have a cameo in this film?
Yes, he does. Peter Jackson appears briefly at the beginning of the film. He is barely recognizable, because of makeup and prosthetics. He is a limping dwarf who tries to escape from Erebor after Smaug has attacked it.