Eric Lensherr: Charles Xavier did more for mutants than you will ever know. My single greatest regret is that he had to die for our dream to live.
When Magneto lands the Golden Gate Bridge on the island, as it hits land it is still very light. When the Brotherhood start to walk toward the island, it cuts to a wide shot of them still walking on the bridge, and it's suddenly dark.
The combat simulation the X-Men are running on their first appearance in the film features the dread Sentinel robots. Originally, these were meant to appear in the second movie already, but the idea was scrapped. The simulation also bears a close reference to the parallel comic storyline Days of Future Past, where the Sentinels rebelled against humanity, killed most of Earth's superheroes and erected a totalitarian regime in the US.