No circularity involved. Approaching the speed of light means that time slows down for the traveler, relative to a stationary observer. Surpassing light speed would (maybe) make time go the other way relative to the traveler. Of course, the traveler's mass would also increase exponentially until the traveler formed a…

I agree that shot complicates things. Say, however, he overshot the target time on re-entry and ended up further in the past than intended. To get back to the moment where Lois is imperiled, he could then fly at near C to get movie time to fast-forward relative to Superman time and drop back in where he needed to. The…

"ridiculous “spin the Earth backwards” conclusion". That's not what happened. Superman just flew faster and faster around the earth until eventually breaking light speed. The camera stayed in Superman time and while from his and our POV, the earth apparently reversed spin, in the movie's reality Superman was simply…