The unprecedented success of the MCU shows no real signs of stopping any time soon. Despite a relative slump in 2021 — a combination of factors including the difficulties all studios are currently facing regarding the pandemic — they closed the year with Spider-Man: No Way Home, which is on track to become one of the biggest box-office hits of all time.

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Despite the studio's great success, making the stories align precisely over 12 years and 27 films (not to mention various TV ventures) is a Herculean task. Add to that the studio's tendency to retcon plot points, and it's no wonder that fans can sometimes get frustrated by the MCU despite its quality.

Iron Man: The Center of the Universe — First Three Phases, 2008-2019

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Despite the presence of the other Avengers in Phase One and the ever-expanding roster of heroes, the fact remains that the rest of the MCU wouldn't have taken flight in quite the same manner without the original Iron Man film. Stylish, funny, intense, and far better than anyone thought it would be, Iron Man set the tone for the early stages of the burgeoning cinematic universe.

This, of course, placed Tony Stark (Robert Downey Jr) at the front and center of proceedings going forward — much to the chagrin of long-time comics fans. While he's an important figure in the pages of Marvel Comics, the MCU essentially retcons him to be the godfather of superheroes — brushing aside (until years later) characters like Hank Pym in the process. More recently, this aspect of the MCU was criticized as it meant Spider-Man became more of an apprentice to Tony rather than letting him stand on his own.

Thunderbolt Ross: Avenger? — 'The Incredible Hulk,' 2008

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Image via Marvel

The cinematic equivalent of the unwanted stepchild, The Incredible Hulk holds a weird space in the MCU canon. While the recent inclusion of Tim Roth's Abomination in Shang-Chi finally acknowledged the Edward Norton-starring introduction to the jade giant, the fact is it's been primarily pushed to the side of thinking in the MCU, especially after the part was recast.

This is why this retcon hurts fans of the character. The Hulk has one of the most exciting groups of supporting characters in the comics, and Betty's father "Thunderbolt" Ross (William Hurt) is no exception. In the post-credits scene, Stark approaches him with a proposal to join the Avengers — this scene was wholly ignored by the wider MCU going forward.

Trevor Slattery is Definitely Not The Mandarin — 'Iron Man 3,' 2013

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After two solo cinematic outings and a team-up, fans were keen to see the 4th outing of Tony Stark — especially given the pedigree of Shane Black, who, after penning the first two films, was given the directing reins in addition to writing this one as well. Given the last time the two collaborated Kiss Kiss, Bang Bang was the result, expectations were high.

RELATED: Kevin Feige reveals Happy Hogan Was Almost Killed in Iron Man 3 Until Jon Favreau Asked to Survive

While it has its defenders many fans disliked this film, primarily for its twist. After Sir Ben Kingsley was cast and confirmed to be playing Iron Man's traditional arch-nemesis, the Mandarin fans were excited to see the character on the big screen finally. For the uninitiated, this was a set-up — Kingsley actually played an actor, who was hired anonymously to play The Mandarin.

Tesseract-Cosmic Cube-Space Stone? — Phase One, 2008-2012

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Comics are never short of a MacGuffin, an object that serves as propellant for the plot. Whether it's to gain power, save one from death, or even bring people back from the dead, these objects are a staple of the genre. However, authors usually define these objects with a particular set of powers, and they're also mostly tied to a specific character. At the very least, they should be distinct.

This is what makes the first phase's "power object" so confusing. First introduced in Captain America: The First Avenger, it is referred to both as a cosmic cube and a tesseract in that film. The cosmic cube is a power object that's been around for decades in the comics. However, once it was decided that the Infinity Sage would form the narrative moving forward, the studio retconned this to be the space stone, leaving fans baffled.

Odin's Gauntlet — Thor Ragnarok, 2017

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On the subject of the infinity saga, this particular red herring has confused and annoyed fans of the MCU almost as long as it's been around. During the first Thor film in 2011, we are shown a glimpse at Odin's treasure vault — including a version of what looks suspiciously like a particular gauntlet worn by a purple, galaxy-conquering alien we had yet to be introduced to.

However, fans were left confused after the post-credits scene for Avengers: Age of Ultron showed Thanos (Josh Brolin) donning another infinity gauntlet. This was finally addressed in Thor: Ragnarok, with Cate Blanchett's Hela flippantly declaring the artifact a "fake." Funny, sure, but it's kind of a lazy way to write off a discrepancy.

Fury Lost His Eye...To a Cat? — 'Captain Marvel,' 2019

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"I'm Nick Fury, director of SHIELD. I'm here to talk to you about the Avengers Initiative." Ever since he stepped out from the shadows during Iron Man's closing moments, Samuel L. Jackson's Fury has been an integral part of the MCU. His distinctive black eyepatch adds to the mystery and overall badassery of the character.

RELATED: The Top 10 Samuel L. Jackson Movies, Ranked

But when it came time for this injury to eventually be explained, Marvel — as it admittedly does have a tendency towards — elected to make a joke out of it. Instead of some heroic scenario involving Fury and losing the eye in battle, Captain Marvel's cat (well, actually Flerken) Goose simply didn't reciprocate Fury's affections and, when he got too close, took his eye out.

Howard Stark: Arms Dealer, Industrialist...Spymaster? — Phases One and Two, 2008-2015

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A lot of Marvel superheroes have daddy issues. In fact, you could argue that it is the trait that defines and unites quite a few of them. Most prominently in this camp, there's Star-Lord (Chris Pratt) and, of course, Tony. Howard (portrayed by Dominic Cooper as a young man and John Slattery as an older man) was at first shown as cold and distant towards his son, prioritizing the development of Stark Industries over his family.

However further installments in the MCU paint the character in a bit of different light — and demonstrate just how much Feige and co. were making up on the fly. During the events of The Winter Soldier, we discover that in addition to running the company, he also co-founded SHIELD — which led to his death at the hands of Hydra.

The Shocking Impermanence of Death — All Phases, 2008-2022

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To be fair, this is something that the MCU 100% shares with its source material. Not that this is an excuse. One of the biggest frustrations for fans — and incidentally why the MCU can often feel like the stakes are pretty light or even non-existent — is the constant fake-outs, revivals, and other write-arounds they've found to make death the equivalent of a bad concussion in the MCU.

Firstly there was the death that started it all, Phil Coulson (Clark Gregg). His death was what stopped the first line-up of The Avengers from squabbling with each other and united them with a single purpose. Coulson was back in Agents of S.H.I.E.L.D. in a matter of months. Since then we've seen characters like Loki (Tom Hiddleston), Pepper Potts (Gwyneth Paltrow), and many others die and then almost immediately — through some writing convenience — come back to life.

Perhaps the most egregious example of course is the events of the last two Avengers films. When Thanos managed to achieve his goal and snap half of the population of the universe out of existence, it was a shocking moment — but it was short-lived, as this course was reversed less than a year later.

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