Audio problem: In the plane, when the Captain says "I'm not too god, what do you think" his lips aren't moving.
Audio problem: While flying with Superman, Lois falls down and starts to shout. When he grabs her, her mouth closes slightly and her expression changes, but the loud crying continues.
Answer: There are generally two methods of time travel. Skip vs Slide. When you slide through time, you are in essence rewinding or fast forwarding a tape. Time will accelerate to the desired moment. This method, the traveler will witness the rewind and will only allow one of them to exist. When skipping, you are plucking yourself from the time stream and placing yourself in the desired moment. This method, travel is instantaneous and can allow for multiples of the traveler to exist at once. Superman rewound time. He used the slide method and went directly to Lois after doing so. This means those he previously saved...died after his reversal.
Or he could have used the skip method. Like you said, it enables a traveler to pluck themself from the time stream and placing them at the desired moment allowing for two Supermen to be able to prevent both missiles from reaching their destinations.
He couldn't have used the skip method if he rewound time.
Bishop73