Mad Men ended weeks ago, but there are still images from the final season that linger in the brain. Arguably, none has stuck with us more than the one of Peggy strutting into McCann Erickson, sunglasses on, cigarette dangling from her mouth, proto-tentacle-porn under her arm. Last night on Late Night With Seth Meyers, Elisabeth Moss talked about how strangely difficult it was to get the shot. Apparently, it was the patting your head and rubbing your stomach of looking badass. Thankfully, she had “Staying Alive” playing. So there you go, nerds, one last secret Mad Men anachronism.