“Zombieland: Double Tap” knows as much as you do that it has emerged in a vastly different world than when its original debuted ten years ago. And that puts it in a position where its very existence seems to be something superfluous. So, Jesse Eisenberg’s Columbus narrates the film with great self-awareness that zombie-lore, both within the narrative of the film and within our world has mutated since then. The opening narration makes us put our guards down. “Yes, we know,” it seems to say. “We know zombies are everywhere now, but allow us some time to riff on them anyhow.” In theory, this sort of ironic deflection might come off as a bit too sure of itself, but the very best thing about “Zombieland” is that even with a sharp tone of irony running throughout, it never feels as if its ironic sensibilities come with dismissiveness. Instead, this sequel that feels both out of place and temporally apt, is best identified by its loose and charming verve – a found family film that articulates the vision of camaraderie in a world turned asunder.