So, a couple things did bug me about this film, though I did like it. I originally thought Magneto's plan for the sentinels was to have them shoot up everyone on the White House lawn, kill Nixon, etc. and make the public thing sentinels were a greater menace than mutants and thus kill the program. Instead, he hovers overhead with an entire fucking baseball stadium while controlling the giant robots, so everyone knows exactly who is doing this, and will only be more against mutants in the future. Good job breaking it, antihero.
But the plot required a reason to re-incarcerate Magneto - correct? Unless I wasn't paying close attention at the end of the film - Magneto heads back to his cell at the conclusion of the film?
The stadium fiasco gives the government sufficient cause to send him back.