Rose Byrne's return in Apocalypse might cause me some issues but if she's had a mutant child in the interim, she might have given up being a CIA agent and become a scientist. They might end up carting her off to Muir Island where she can... er... develop false accent syndrome or something or maybe be telepathically convinced that she's Scottish. That might smooth it over for me.
The thing that always confused me about Moira was how she looked like Rose Byrne in
X-Men: First Class but 40+ years later in
X-Men: The Last Stand she looks like Olivia Williams!

In terms of aging, that's practically a lateral move! (I wasn't quite as bothered by where she got the British accent. I figured she just somehow stole it from Carol Marcus.) Then I realized, the answer was staring us in the face the entire time. During her scenes in
The Last Stand, she & Professor Xavier are talking about the morality of a telepath transferring one person's consciousness into another person's body. I figure that's what happened to Moira. Some time between
First Class &
The Last Stand, Moira's original body was mortally wounded by some bitchy young mutant girl. Xavier got pissed and so he transferred Moira's consciousness from her dying body into the body of the amoral mutant that killed her.
Although, considering
X-Men: Apocalypse is asking us to believe that James McAvoy & Michael Fassbender are 50-year-olds, maybe people just don't age normally in the
X-Men movie universe.
Bryan Singer has said himself he considers the X-Men films to constitute a rather loose continuity.
I'm actually kind of impressed at how cohesive it feels despite that. The discontinuities mainly apply to background characters and easily overlooked details.
I'm pretty impressed too. In particular, the stuff in
Days of Future Past with the serum fixing Xavier's spine does a brilliant job of reconciling the end of
First Class with the later scenes of Xavier walking in
The Last Stand &
X-Men Origins: Wolverine. It also reconciles Beast's transformation in
First Class with the brief appearance of human Beast on the TV in the bar in
X2.
There's other stuff that's harder but a lot of it is minor details that we just have to ignore. (I.e. Xavier said he met Magneto when he was 17 in
X-Men yet seems to be much older in
X-Men: First Class.) I often have to just separate characters. Like, Emma Frost in
X-Men: First Class is a totally different person from Kayla's sister in
X-Men Origins: Wolverine. And Victor Creed & Sabertooth are not the same person in the movies.
Pretty much. I've seen people complain that some unnamed but recognizable character appeared in one of the other X-Men films, therefore they can't have been born yet in this film (or whatever.) Because maintaining strict continuity even with costumed extras who spoke no lines is paramount!
Everyone needs to chill out about Jubilee. Especially because, knowing her luck, she'll end up getting cut out of this movie too.
