2. Increased Role of Galadriel and The White Council
It appeared that Gandalf had been to a great council of the white wizards, masters of lore and good magic; and that they had at last driven the Necromancer from his dark hold in the south of Mirkwood... - The Hobbit
Background The White Council of The Hobbit was a group of seemingly allied members of the Istari and Elven Lords that joined forces during the Third Age to counter what they perceived to be the escalating hazard and darkness emanating from the fortress of Dol Goldur. Technically this group was The Second White Council- for the First White Council (of which very little is formally known) had formed in the Second Age, prior to the arrival in Middle-earth of the Istari. The Council first met in 2463 (following dates are all now Third Age) to counter the growing threat in Mirkwood. Gandalf trekked through Mirkwood in 2850, and discerned that the Necromancer was in reality Sauron taking shape again. The Council reconvened to decide whether to act on Gandalf's discovery but Saruman discouraged this, which further increased Gandalf and Galadriels deepening distrust in him. Eventually Saruman relented, realising that Sauron might recover the One Ring and regain his strength, knowing after which any form of resistance would be futile. The Council responded by driving Sauron out of Dol Goldur (though in essence Sauron feigned this defeat). He fled to Mordor and his newly repaired tower of Barad-dûr just prior to the events of The Lord Of The Rings.
Film vs Book Galadriel is never mentioned in the The Hobbit book and The White Council is only alluded to in when Bilbo surmises from the talk between Elrond and Gandalf that they had been to a great council of the white wizards The appendices and other supporting material explain that The Second White Council's membership included the members of the Istari discussed above- Saruman, Gandalf and potentially Radagast, and the key rulers of the Elves including Galadriel of Lothlórien, Elrond of Rivendell and Cirdan of the Grey Havens. From the promotional material that we have seen of the movie we can see Elrond, Galadriel, Gandalf and Saruman in discussions around a table in what looks to be Rivedell, so were likely to see a smaller version of the Council than that which Tolkien wrote about. This is understandable, since getting the viewer acquainted with 13 dwarfs over the course of one movie will be tough enough, without adding in additional characters who are largely unnecessary to the progression of the story- so the Council will likely be made of characters that we already know from LOTR, and maybe to a lesser extent Radagast. Saruman was appointed the head of the White Council, and we know from supplementary material that this happened against the wishes of Galadriel, who later described this as the beginning of their long defeat. Galadriel likely divined in Saruman that he secretly held a lust for power, and would have preferred Gandalf to have been the head of the order: in his spirit form back in Valinor, Gandalf- or Olorin as he had then been known- had initially been reluctant to journey to Middle-earth, since he was afraid of Sauron. The Valar believed that this was all the more reason why he should have been a member of the group that departed from Valinor in order to match Sauron. The above key events (the protracted debating and developing distrust amidst The White Council, the identification of the Necromancer as the returning shadow of Sauron, and the Battle of Dol Goldur) are only at best hinted at in the book, but are likely to form key scenes in the movies, showing the visual representation of why Gandalf was unable to accompany Bilbo and the dwarves on their trip to the Lonely Mountain.