Dark Phoenix marks the 13th installment into the X-Men film franchise if you include both Deadpool and Deadpool 2. The majority of these movies were well received by critics. However, there's no denying that they've left plenty of unanswered questions for loyal fans. Some are just storylines left unresolved, while others are part of the massive continuity errors seen throughout the nearly twenty-year history of the series.

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After going back and watching each film again, we've come up with ten storylines that have yet to be resolved. With the property moving to Disney and on track to getting rebooted when it joins the Marvel Cinematic Universe after Dark Phoenix, there's a good chance we'll never find our answers.

The Cure

One of the two main storylines during X-Men: The Last Stand revolved around a cure being created for the mutant gene. Some have questioned this taking so long to happen because Hank McCoy and Charles Xavier had a serum in the 80s that could temporarily do this. However, it makes sense that they would keep that to themselves and not willingly give that out.

The bigger unanswered question revolves around what happened to it. Humans were weaponizing it against mutants. Yet, in the timeline shown in X-Men: Days of Future Past, the Sentinels are out killing mutants in cold blood. The cure should remove the need for sentinels to be killing machines. It should at least be mentioned since it had already been established.

Mister Sinister Tease

In the post-credits scene of X-Men: Apocalypse, the arrival of a major villain is hinted at. A man takes a vial of Wolverine's blood and places it in a briefcase marked "Essex Corp." Any X-Men fan understands that is a reference to Nathanial Essex, better known as Mister Sinister.

Director Bryan Singer stated that the scene was done to introduce Minster Sinister for Logan. That never ended up happening and this is never mentioned again. What happened to Nathaniel? What was done with Wolverine's blood? It's a shame because this is arguably the biggest X-Men villain to never grace the big screen.

The Many Errors Of X-Men Origins: Wolverine

Pretty much everyone can agree that X-Men Origins: Wolverine is the worst installment in this franchise. There are several issues including poor CGI, lousy writing, a mess of a plot, and the character assassination given to many favorites. But the most significant problems lie in continuity.

How can Professor X walk when we see that he becomes paralyzed at a much younger age? How does Wade Wilson have his mouth sewn shut and his head cut off, only to become the Deadpool we all know and love a few years later? Why does Cyclops have his powers here when they only manifest for the first time a decade later? How is Emma Frost in her 20s in Origins but in her 30s during X-Men: First Class, which was a decade earlier? Sheesh.

Charles And Raven's Friendship

One of the most prominent ongoing threads through the prequel trilogy is the friendship between Professor X and Mystique. In it, Charles took in Raven as something of a foster sister when they were young and they grew up together. Though Mystique joins Magneto's side at the end of X-Men: First Class, the two remain friends.

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When they see each other in the next two films, they have friendly conversations and Charles manages to talk Raven down before she murders Bolivar Trask. Despite all of this, their friendship is never touched upon when they're older. Did something happen where one of them lost these memories? When did they reach the point of no return that changes their relationship so dramatically?

Cerebro

Cerebro is the device used by Professor X throughout the series to connect to mutants all around the world. It is used in both the original and prequel trilogies. The story of its creation is muddled and could use some explaining.

Initially, we heard that Magneto helped Charles build Cerebro. When we see it in the past, it turns out that a young Hank McCoy made the device. Magneto was around when Charles first used it, but that's hardly creating it. Even when we see it in later stages, Magneto barely plays a part. What gives?

Magneto Gets The Cure

As mentioned earlier, the mutant cure is a vital part of X-Men: The Last Stand. In that film, Wolverine and Beast team up against Magneto, and the only way they can stop him is to inject him with the serum. For someone who has always worn his mutant ability as a badge of honor, this was a considerable loss.

At the end of the movie, Magneto moves a metal chess piece with his mind. That suggests the cure wasn't permanent and when we next see him, his powers are back in full force. An explanation is never given for any of this.

Dark Phoenix Again?

Obviously, the main plot to Dark Phoenix centers around the famous comic storyline where Jean Grey is taken over by a powerful cosmic entity known as the Phoenix. It's a wildly popular story arc that seems tailor-made for the big screen. Maybe that's why they've done it twice.

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Redoing storylines in comic book movies isn't new, but doing so in a franchise that supposedly shares continuity is completely different. In X-Men: The Last Stand, Jean Grey is taken over by the Phoenix, an alternate personality. Judging by the Dark Phoenix trailers, it follows more of the cosmic comic origins. Did the Phoenix take over Jean twice, in different ways? It doesn't make sense and it doesn't seem like we'll ever find out what's up.

Wolverine's Claws

2013's The Wolverine was a big step up from the first solo Wolverine film. Taking place in Japan, Wolverine does battle with a giant adamantium robot. During the fight, he gets his claws cut off. His original bone claws grow back due to his ability to regenerate and he wins the battle.

Logically, that's all fine. But when we next see Wolverine, it's in X-Men: Days of Future Past. Crucially, he has his adamantium claws. How is this possible? He also has them during the events of Logan, which takes place much later down the line. Fans everywhere want to know how he got his claws back, but we'll never find out.

Professor X Is Alive

Again, we're looking to X-Men: The Last Stand. In it, Jean Grey's Phoenix takes over and she brutally destroys Professor X. He's not just killed in this altercation, she obliterates and disintegrates him in front of everyone, though he gives a weird look to the camera before this happens.

All of a sudden, Charles is alive in the next few films in the timeline. We get a cheap explanation that he can move his consciousness to another body, which is how he wakes up at the end of X-Men: The Last Stand. However, is that an identical body? There were rumors of a twin, but is that body also somehow paralyzed?

Mystique Captures Wolverine

The biggest storyline left unanswered came at the end of X-Men: Days of Future Past. It had nothing to do with complicated time travel or timeline confusion. At first glance, nothing seems wrong. Wolverine is taken by William Stryker, who we all know is the person who tortures him, as well as gives him the adamantium. The mind-boggling part is that Stryker's eyes flash yellow, indicating that it's actually Mystique disguised as him.

That throws all logic out the window. Mystique has no reason to do this as she wants to liberate mutants. In the next chronological movie, X-Men: Apocalypse, Wolverine is being held captive after getting the adamantium by the real Stryker. What happened during those two movies to get him from Mystique to Stryker and why did Mystique do this in the first place?

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