The X-Men movie series has too many continuity failures to count here, but one claimed failure I don’t think is actually one.
I’ve seen people online complaining that it’s inconsistent for Jean Grey’s powers to have manifested in the shape of a phoenix back in Age of Apocalypse when she didn’t get infected with the Phoenix Force until Dark Phoenix.
But I think this complaint comes from viewing the films through the lens of the comics. In Dark Phoenix, the force that infects Jean is never called the Phoenix Force, nor is it shown taking the shape of a phoenix prior to its encounter with Jean. So the phoenix aspect, in the films, seems to come entirely from Jean, and is something awakened or triggered by, rather than contributed by, the force that infects her. FWIW, that’s also more or less consistent with Last Stand, where the Phoenix Force was something innate in Jean all along and only triggered by the events of X2.
Just wanted to add this pic: