Why did everyone in that comic take their stupid pills that morning? And most of them took their out-of-character pills, too. Why was every currently-published hero invited, but not out-of-print characters (former JLAers, former Birds of Prey, more Green Lanterns, etc)?

But the one that really grates on me? Why does one of the greatest martial artists in the world, whose style is specifically designed to avoid killing, who has a metahuman ability that can easily knock someone unconscious at close range, have no other option but to randomly grab an arrow and kill the man she thinks is her husband?