Question: Why did Storm turn on Apocalypse?
Chosen answer: She only followed him because he claimed to care for mutants. When Angel dies, Storm hears Apocalypse's remark and is insulted. It is then clear to her that Apocalypse doesn't really care about mutants and he is simply using them for their power.
Question: Why did Magneto need his old helmet if Apocalypse can shield minds from Charles' telepathy?
Chosen answer: Because it's part of his costume.
Question: How does Stryker know that Charles Xavier is the world's most powerful telepath? They only met during the 70s and Charles never used his powers in his presence.
Answer: As shown in Days of Future past, Trask was able to identify Magneto and Mystique, as well as their mutant powers. Trask could have found Charles Xavier at any given time, or Stryker possibly researched him. Stryker did work for Trask after all.
Question: Did Apocalypse give Magneto new powers in Poland, or just enhance them?
Chosen answer: Neither, actually. Apocalypse merely revealed to Magneto a way in which he could use his powers at their current level. Magneto is simply phenomenally powerful.
Question: When Jean Grey says the third movie in a franchise is always the worst is this a joke on all franchises as well as X Men: The Last Stand?
Answer: Yes, this is a thinly veiled jab at X-Men: The Last Stand. That film had a notably poor reception among fans and critics and at that point was generally considered the worst of the X-Men films. Ironically, X-Men: Apocalypse was also poorly received and is technically the 3rd film in the "First Class" series.
Answer: She's not making a joke. Sequels are often criticized because the more that are made from an original movie, the greater the decline in the quality. The scripts are often repetitive and unoriginal, and the purpose seems to be only to make as much money as possible with the least amount of creativity or effort.
Question: Why do they keep changing Mystique's appearance in this branch of the franchise? Compare First Class to Dark Phoenix, notice the difference.
Answer: Jennifer Lawrence was actually allergic to the makeup that was used on her in First Class. For the next two films, she wore a body suit instead. For Dark Phoenix, since they were just going to kill her character off anyway, I think they just decided to be lazy and went with a more minimal approach with her appearance, and didn't care that it looked different. I mean, the scene of Jean Grey being taken over by the Phoenix Force at the beginning of Dark Phoenix directly contradicts her having the Phoenix power at the end of Apocalypse, so it's not like the filmmakers cared too much about overall continuity in the series.
Question: I don't get why Jean treats Scott coldly and then they become friends all of a sudden?
Answer: Jean reads minds, so she might read his mind at the first encounter and realised that he was arrogant at the time and not very fond of the place that his brother took him.Also Jean was cold with everyone because of her powers and that every person there afraid of her.
Question: How come Eric reformed?
Answer: Mystique got through to him. And his loyalty to Charles overrode any and all false allegiance he had with Apocalypse. Blood being thicker than water and all that. He had all that history with Charles.
Answer: He realised the mutants he was helping Apocalypse fight against had always been there for him.
Answer: Psylocke is purposefully shown literally just walking away after the dust has settled. She could very well show up in another film somewhere along the line but nothing has been confirmed as of yet.
BaconIsMyBFF