2. Pick An Approach To Continuity (And Stick With It)
Right from the get-go, director Matthew Vaughn had a clear approach to fitting First Class in with the continuity of the original trilogy and consistently stuck with it through the script. As with comic books approaching earlier editions of their franchise, he took a broad strokes mentality. It was a prequel, but it was also a reboot. In other words, never let the original canon get in the way of a good story. That said, the minds behind First Class obviously still have respect for the original trilogy and so this is seen in their characterization of young Erik, Charles and Raven. Though the events they go through in First Class were not imagined as part of their back-story in the original trilogy, and yes, go against things said in those films, the seeds of their behaviour and decisions in the trilogy can be seen in First Class. The original trilogy at times contradicts itself for example, in the background of X-Men United, we see Dr. McCoy, fully human and on the television, whereas in X-Men: The Last Stand hes played by Kelsey Grammar and noticeably bluer.
By openly taking a broad strokes approach, the minor toe-stepping and canon violations usually created by throwaway lines Erik and Charles dont meet when Charles is 17, Erik doesnt build Cerebro - can be ignored except by the most pedantic fans. This is an approach Id like to see more in a world becoming increasingly filled with prequels. The teeth gnashing that occurred after the announcement of Monsters University when, a single line in Monsters Inc. was supposedly violated as Sully and Mike were shown meeting at college rather than in fourth grade. It was almost instantly quelled when Pixar told fans to simply get over themselves or pretend it was a monster-world expression. Never let the truth get in the way of a good story. More of that please.