Super Serum Plot Hole Fixed
In the original comic, they never explain how Luthor got the same super powers as Superman. He just had it and made it in prison.
They fixed this plot hole in the movie. Luthor infiltrated the Fortress with Number 7 and stole some of the serum, and changed it to his DNA structure.
I thought this was a nice touch, and definitely connects Lois' birthday to the ending rather well.
This still leaves the other Kryptonian explorers plot line rather bare from the rest of the movie.