Superman Returns, the BIG PROBLEM
Why is everyone ignoring the big problem with "Superman Returns"?
The premise of the movie is that Superman left the Earth for 6 years in order to fly back to Krypton to see if it was still there.
*Ahem!* Superman gets his powers from the Earth's yellow sun, so if he were to fly out of the solar system, he would loose his power.
Even if he were able to maintain his power for three years in deep space, away from the supercharging effects of yellow solar radiation, he would still loose them as he approached Krypton's red sun.
Either way, he would die, unpowered, in the cold vacuum of space.