The question of whether to use them is a toughie. Things to consider are 1) the shots aren't in the comics, 2) there's a good argument to be made that flashbacks of that particular variety aren't common to the comics, and 3) there's just as good of an argument to be made that such flashbacks ARE common to the comics. Not sure what my call would be.
If the goal is to just make the flick BETTER, I'd say definitely use them.