CW’s Whose Line Is It Anyway? may be the worst at cramming its own network celebrities into a game show for easy cross-promotion, but this NBC entry, at least tonight, gives it a run for its money in the shameless promotion department. Guests include Today weather guy Al Roker and America’s Got Talent host Nick Cannon. But you also get, thank goodness, Jason Alexander, who shows up ready to play, and with more hair than usual.