Superman II: The Richard Donner Cut (2006 Video)
The next scene we see is meant to be the beginning of the movie again, with the Daily Planet - so after the nuclear explosions, and before the arrival of the villains - but Clark goes back to straighten out the trucker who hit him afterwards - though because Superman turned back time, basically, this event never happened - so Clark was hitting an innocent man for no reason. (The diner owner says that he just had the place fixed up - meaning the scuffle did occur, and Clark claims he's been working out, meaning from the last time they saw him, when he was beaten - however, again, this never happened because Superman turned back time again.)
Moreover, towards the end of the film, Superman destroys the Fortress of Solitude with his heat-sight - the Fortress of Solitude should be reconstructed (and with Jor-El available to guide Kal-El again) due to Superman turning back time again. The time travel device, beyond complicating the film's time-line, nullifies Jor-El's sacrifice and Superman's lesson, as after turning back time, things should be "back to normal" again.
Furthermore, if Superman's end-game was to turn back time all along, he didn't have to fight the super-villains in Metropolis or in the Fortress of Solitude at all - he could have turned back time immediately after regaining his powers, or following the Metropolis fight.