I wish they'd have shown the full sentinel in the Danger Room scene. Also, if they were to make a 4th movie, they could give Rogue her super strength and flying ability and just explain it away as her powers coming back and being even stronger than before. If Magneto became even more powerful it could open up the whole bit about when he stripped the adamantium from Wolverine's skeleton and then they'd discover he had his claws the whole time. (Plus how awesome would it be if he's fighting people with his bone claws and they keep regenerating anytime they'd break or something)