Are there any flashbacks in the book, The Hobbit? The movie starts out with one, but that is not seen in the book.
At this stage I'd guesstimate that perhaps 75% of movie content isn't actually in the book.
The book is an almost totally linear adventure, with the first half consisting of largely disconnected episodes (or "adventures") and the second half becoming a more connected narrative. The "adventures" in the first half don't have much bearing on the second half, aside from providing a means of acquiring a magic item or two, giving a sense of danger in the course of getting from A to B, or introducing a character who's going to reappear later.
There are three main incidents which are narrated after-the-fact (Smaug's attack, (most of) the Battle of Five Armies, and the Assault on Dol Guldur) but these are not handled as direct flashbacks. The Assault in particular is just a single sentence describing where and why Gandalf was away.
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.
So your answer is "No".