A sincere question for my readers: is it worse for a movie to be derivative or lifeless? The Watch, the second feature by The Lonely Island’s Akiva Schaeffer, borrows liberally from science fiction cinema classics like Invasion of the Body Snatchers (take your pick between the ’56 and ’78 versions) as well as contemporary greats like last year’s excellent Attack the Block, but the film’s worst transgression isn’t its unapologetic mimicry. Calling on decades-old genre traditions is one thing; turning out an embarrassingly brainless, thoroughly bland, and criminally unfunny attempt at sci-fi comedy is another entirely. The Watch shows as little interest in its aliens as its punchlines. Not to mention its characters. Like the best…