Superman reverses time!
That was a horrible movie. For decades the comics had well-established that Superman could NOT change the past. Somehow he would be thwarted, or what he did had actually already happened but he didn’t know it. This was done because once Supes can change the past, he would try to save his Kryptonian parents, and then they would not have sent him to Earth, and then he would not be Superman. Bad enough he was trying to stop ALL crime, attend charitable events, AND work full-time as a mild-mannered reporter for a major metropolitan newspaper. It was a good rule, an ESSENTIAL rule if you want Superman to travel to the past. But Warner and Mario Puzo did not respect the original material, and never understood comic book readers, and didn’t really care to.