“Saturday Night Live” kicked off its 48th season with a cold open that acknowledged an off-season of change in which several stars departed and a team of newcomers joined the huddle. The show began with a parody of ESPN2’s “ManningCast” where former Giant Eli Manning and his superstar brother Peyton Manning offer analysis of each week’s Monday Night Football game. But on “SNL,” the pair, featuring “Top Gun” star Miles Teller playing an uncanny version of the latter Manning, pretended to analyze a sketch featuring cast members that will be seen on NBC every Saturday night in coming months. That…