1) Magneto Says Goodbye for Some Reason
Like the other Horsemen, Magneto’s motivations aren’t often clear in X-Men: Apocalypse. He goes from a reformed family man to an avenging villain in a matter of seconds, from a moody welder living in rural Poland to one of En Sabah Nur’s genocidal cronies, all as a result of one single act. Then, inexplicably, he turns on Apocalypse at the end of the movie, firing two girders at him that defiantly spell out the letter ‘X,’ before helping the X-Men to utterly wipe the big bad out.
It’s nonsensical, but at least we in that moment know which side Magneto has chosen to be on, who he has accepted as his ‘family,’ Finally, Magneto’s motivations seem clear. So, why does he then turn away from Charles and his mutant friends at the end of the film? Where exactly does Erik have left to go, and why would he want to go there when he’s just re-allied himself with the X-Men?
Clearly Singer wants to keep the option of having Magneto as a future villain open, but it makes absolutely zero sense for the character in that moment.