In the climax of the film, we see Hoover Dam break, threatening to wipe out a town in minutes with the water from the lake. Fortunately the water is flowing through a canyon which Superman is able to dam with rocks just in the nick of time, saving the town.
While all this is happening, Lois is in trouble. After creating the rock dam, Superman rushes to save her, but arrives too late, and she is dead. He cries, then screams, then turns back time.
While time is running backwards, we see Lois' death, the creation of the rock dam, and the failure of Hoover Dam running in reverse. Then when time starts moving forward again we see Superman go take care of Lois then fly off to deal with Luthor. We never see or hear anything about the dam, the canyon, or the town.
My question: Does the time-travel trick allow Superman to be in two places at once, or does he sacrifice the town to save Lois?
I wonder if it was left intentionally ambiguous. On the one hand, Superman sacrificing hundreds to save one seems inconsistent with the tone of the film. On the other hand, it would validate the advice he gets from his father in the next film that he must choose between being Superman and being with Lois because “You cannot serve humanity by investing your time and emotion in one human being at the expense of the rest.” (That quote is from the Donner cut, but Superman hears something similar from his mother in the original theatrical cut.)