Other mistake: The first ten minutes of the film you can see where the make-up stops at the top left of Bella's hairline.

The Twilight Saga: Breaking Dawn - Part 2 (2012)
Trailers
Directed by: Bill Condon
Starring: Kristen Stewart, Robert Pattinson, Maggie Grace, Taylor Lautner, Peter Facinelli






Answer: It would be rather difficult for the small number of vampires that exist to kill six billion humans. Even if they could, they would be eliminating their food supply. As to the Volturi, it's unlikely all three would die and at the same time. It's probable that a line of succession is in place to replace them. There are other vampires working within the Volturi organization that we don't happen to see.
raywest ★