I think I am supposed to say that Bill & Ted Face the Music, the third in a franchise about two Californian morons who time travel to save the world, is a harmless satire on American teenage good-naturedness and stupidity. I’m not sure about that: I think it is more likely evidence of what American cinema has done to the American mind since Jaws turned the B-list film into the A-list film, and vice-versa.