On the surface, “Paul” (2011) is a funny twist on the timeless story of an extraterrestrial trying to get home. Below the surface lurks Seth Rogen. That means R-rated hilarity, snappy dialogue, the obligatory pot-smoking scene and waaay too much cussing. Frankly, just waaay too much of whatever it is that makes the first 75 minutes of Rogen’s movies so funny and the last 25 a chore. Maybe I shouldn’t have watched the unrated version. Maybe they shouldn’t have MADE an unrated version. Anyway, it was another case of seeing skilled surgeons perform an intricate operation while wearing oven mitts.