NFL and sports in general are not scripted but I know without a doubt there's crooked refs out there and crooked players. I can tell you right now without a doubt that NFL ref Clete Blakeman has fixed games. 100% without question and there's evidence out there to support this claim if you dig deep enough. I have seen so many shady things happen in games he officiates going on for over a decade now. And he's always the common denominator. Then you see reports around Vegas that large money line bets were placed on games specifically officiated by him, and those tickets always won, with frequent complaints about awful, suspicious calls made by Blakeman. Desmond Howard even publicly called for him to be investigated.
He isn't the only one. Basketball games getting fixed all the time, especially at the college level. Not usually fixed for a winner or loser per say, but more the over/under. It's very easy for officials to call a game that influences the total, and they can still keep some integrity by letting the better team win, albeit by a score they are happy with.