Studios often spoil major plot reveals before the credits even begin. Marketing departments and critics reviews cant help themselves when they tout the major twist within. But whats worse is a twist you see a mile off when a certain actor or actress is cast because they've played a similar role many times over. Typecasting has its pros and cons. It lands good actors more work because directors and casting directors know they can pull off the role again. And on a small scale, thats all well and good. Having seen Michael Cera act in Arrested Development, youd have no problem believing he could play the awkward teen in Juno. But when that typecasting is tied up with major plot reveals, the effect is obvious. That totally shocking and unexpected twist youve got in the third act becomes very predictable. And in the worst cases, its predictable not even from the introduction of characters in the first or second act, but from when the casting announcements are made. Spoilers obviously lie ahead, so proceed with caution. (But chances are you couldve guessed the plot reveals anyway.)
Honourable Exception: Kevin Spacey Se7en
This is how you do things right, and serious hats off to David Fincher and Kevin Spacey for the way they handled this. In the opening credits, when youve got Brad Pitt, Morgan Freeman, Gwyneth Paltrow, and everyone elses names cropping up, the one name you dont see is Kevin Spacey. His name is held back for the end credits, because if you have someone as well-known as Spacey billed in the opening titles and he doesnt show up for most of the film, youre going to assume pretty quickly that hes the mysterious John Doe that Brad Pitt and Morgan Freeman are hunting. Well played, folks.