Plot holes solved:
Magneto helped the X-Men against Apocalypse in Cairo and he was forgiven for his crimes.
Jean Grey just cut herself by accident during the battle and it took time for the blood to come out of the skin and stain the shirt. The blood on the shirt is hers not Mystique's.
(but seriously that last plot hole was a pretty bad editing mistake, production-wise this movie has serious flaws)
Miguel Evaristo, Jean was shown with blood on her hands. She was trying to wipe it off with her shirt it seems.
Are you sure? I slowed-down the image and I couldn't see anything. Plus, she would definetly have dried blood on her hands anyway.
What do you think?