Would spinning the earth backwards really cause time to flow backwards?
I believe that the idea in the Superman movie was that he, by travelling at the speed of light – or perhaps even faster – started to travel backwards in time. As he travelled backwards in time, the earth, to him, appeared to be turning backwards. So if you could travel back in time AND still observe the earth whilst doing so, it would appear to spin backward but would nevertheless still be obeying the laws of physics which are, as far as I know, time reversible. So spinning the earth backwards would not cause time to reverse. Reversing time would cause the earth to appear to spin backwards.