Will 'Avengers: Doomsday' Be Steve Rogers' Fault? 10 Greatest Mistakes Made By Heroes In The MCU

Fans attending this year's CinemaCon were treated to an exclusive first-look trailer for the upcoming MCU blockbuster Avengers: Doomsday. As others eagerly await a wider released trailer (to follow the four existing character teasers), speculation on the film's plot has once again ramped up. One of the most prominent recent theories is that the increase in Multiversal Incursions, the biggest and most dangerous recurring issue of the Multiverse Saga, may have been inadvertently caused by Steve Rogers' decision to go back and have a life with Peggy Carter at the end of Avengers: Endgame.

Having Steve, the former Captain America and one of the MCU's greatest and most morally grounded heroes, having to reckon with the fact that his actions may have threatened the universe, could add an interesting twist to his return in Avengers: Doomsday. However, Steve is far from the only MCU hero to have made such a mistake. Here are some of the greatest mistakes made by our heroes through the history of the MCU.

1. Tony Stark creates Ultron (Avengers: Age of Ultron)

Following the events of the first Avengers film, Tony Stark develops PTSD and a deep fear of future alien invasions. This results in his work with Bruce Banner to create Ultron, initially intended as a peacekeeping program. When Wanda Maximoff forces him to experience a vision of a dark potential future, Tony convinces Banner that they can use Loki's recently recovered sceptre (which contains the Mind Stone) to fast-track the creation of Ultron.

This is, as longtime MCU fans will be aware, a big mistake. Rather than the intended peacekeeping program, the Ultron A.I is homicidal and highly unstable. Aiming to end the Avengers, Ultron's existence leads to a large chunk of the country of Sokovia being destroyed, and the death of Pietro Maximoff.

Ultron continues to have an adverse affect beyond Avengers: Age of Ultron, with the fall of Sokovia making Tony more amenable to the idea of placing the Avengers under U.N control in Avengers: Civil War.

2. The Lagos Incident (Captain America: Civil War)

The Avengers find themselves on thin ice with the rest of the world after the events of Sokovia. However, they are unaware just how thin until a mission in Lagos goes awry, with Wanda Maximoff unintentionally partially destroying a building of innocent people while struggling to contain an explosion.

The accident didn't directly cause the Sokovia Accords (a bill placing deployment of the Avengers under U.N durisdiction). They had already been written up, and named, after Sokovia. It was, however, the straw that broke the camel's back as far as the Accords becoming law, leading to the Civil War that fractured and disbanded the Avengers.

3. Loki stealing the Tesseract (Thor: Ragnarok)

Loki first steals the Tesseract, a powerful object containing the Space Stone, in the opening scene of the first Avengers film. He also, notably, steals it again when the first film is revisited in Avengers: Endgame, resulting in a branch timeline that leads into the Loki TV series. A long-running fandom joke even references Loki and the Tesseract as one of the MCU's greatest love stories. However, it is his second theft of the Tesseract that marks the God of Mischief's biggest mistakes.

While dropping Surtur's crown into the eternal flame in Thor: Ragnarok, a mid-redemption arc Loki finds and steals the Tesseract from within Asgard's vault. This theft is not revealed until the opening scene of Avengers: Infinity War, when Thanos's forces attack the Asgardian refugee ship, kill half the Asgardians, and badly injure Thor. Thanos then murders Loki and steals the Space Stone from inside the Tesseract.

It is his possession of the Space Stone that allows Thanos to so quickly and easily travel between the various different locations in Infinity War. If Loki had not stolen the Tesseract, it and the Space Stone would have been destroyed with Asgard. While this would not have necessarily thwarted Thanos's plans, it would have delayed him significantly. It also would have taken away the biggest reason for the attack on the Asgardian ship, meaning Loki himself could have lived.

4. Star-Lord ruins the plan (Avengers: Infinity War)

At one point, the group of heroes on Thanos's home planet, Titan, including representatives from both the Avengers and Guardians of the Galaxy, concoct a plan to separate Thanos from the Infinity Gauntlet, as well as the three Infinity Stones he had gathered at that point in time, by temporarily putting him to sleep. The plan very nearly works, until Peter Quill, aka Star-Lord, learns that Thanos had sacrificed the life of Gamora, his adopted daughter, and the love of Quill's life, to obtain the Soul Stone.

Quill attacks Thanos, waking him just seconds before his allies would have successfully removed the Gauntlet. From that point onward, things take a turn for the worse for our heroes on pretty much all fronts. Some fans even blame Star-Lord entirely for the heroes' loss, despite his mistake being part of Doctor Strange's single chance at victory scenario.

5. Thor didn't go for the head (Avengers: Infinity War)

Thor spends the majority of Avengers: Infinity War eager to seek revenge on Thanos for the murders of Loki, Heimdall, and half the Asgardian people. He very nearly succeeds, driving his new axe, Stormbreaker, deep into Thanos's chest during Infinity War's final battle. Unfortunately, Thanos had just successfully obtained all six Infinity Stones at the time.

"You should have gone for the head."

Thanos taunts Thor, before performing the snap of the fingers that successfully wipes out half of all life in the universe. The failure haunts Thor deeply in the five-year jump between Infinity War and Endgame.

6. Sending Nebula to 2015 (Avengers: Endgame)

During the Time Heist plan, Nebula travels with Rhodey to the planet Morag in the year 2015 to collect the Power Stone. Unfortunately, Nebula's cybernetic implants entangle with those of the past Nebula, still loyal to and eager to please Thanos. This leads to future Nebula's capture, the theft and reverse-engineering of the Pym Particle, and past Nebula switching places with her future counterpart, bringing Thanos and his army through the time tunnel to the future.

This obviously wasn't a conscious mistake on the part of the heroes. They had no way of knowing the entanglement was a possibility, and at surface value, it would have seemed like a good idea for Nebula to travel to a time and place she knew better than other Time Heist participants. However, that doesn't change the fact that this was the greatest threat to the Avengers' victory that occurred in the entire film.

7. Peter Parker hands E.D.I.T.H to Mysterio (Spider-Man: Far From Home)

Following his death in Avengers: Endgame, Tony Stark wills the E.D.I.T.H (Even Dead I'm The Hero) glasses to Peter Parker. These glasses give Peter access to large amounts of information, and a fleet of Stark drones. They came with a note:

“To the next Tony Stark, I trust you.”

Unfortunately, due to a series of smaller missteps he makes throughout Spider-Man: Far From Home, Peter comes to believe that Tony did not intend for him to keep the glasses, but rather to find the right adult to carry them. He chooses to hand them to Quentin Beck, aka Mysterio, a Stark-like hero supposedly from another universe. What Peter doesn’t realise is that Beck has been manipulating everyone the whole time. He is actually a disgruntled former Stark Industries employee planning to use the drones to stage an attack and position himself as the Earth's next great hero.

Peter does realise his mistake and defeat the villain, but not before Beck and his followers enact a plan to expose Peter as Spider-Man, the fallout of which follows Peter into Spider-Man: No Way Home.

8. The Memory Spell (Spider-Man: No Way Home)

When Peter Parker's identity as Spider-Man is revealed, his life, and the lives of those around him, become complicated. Peter visits Doctor Strange for help, and Strange, at first sympathetic, offers to cast a spell that will make everyone forget Peter is Spider-Man.

However, Strange neglects to discuss anyone Peter would like omitted from the spell prior to casting. This leads to the rather dangerous situation of altering the spell during casting. The spell becomes unstable, eventually leading to cracks in the universe which villains from other universes begin to slip through. This eventually leads to the film's rather tragic ending, in which Peter allows Strange to repair the cracks in the universe via a spell that makes everyone forget Peter Parker.

Strange blames Peter for the failed spell initially, until MJ points out it is at least partially his fault for casting the spell in the first place. Most fans lean towards attributing blame to Strange, as he is the one with the magical expertise, and should have hashed out the details of what exactly Peter wanted from the spell before he began casting.

9. The Illuminati ignore Strange's Warning (Doctor Strange in the Multiverse of Madness)

During the events of Doctor Strange in the Multiverse of Madness, Doctor Strange and his teenage charge America Chavez are transported to Universe-838. There, they are taken into custody by the Illuminati, a group of 838's greatest superheroes overseeing the safety of their universe.

Strange desperately attempts to warn the Illuminati of the impending arrival of the Darkhold corrupted Wanda Maximoff, who is pursuing America to steal her multiverse-hopping powers. The Illuminati disregard Strange's warning, believing him a greater threat than Wanda as their own Doctor Strange once destroyed another universe by causing an incursion.

They probably wish that they had listened, as the entire team is slaughtered by the Scarlet Witch a few scenes later.

10. Reed tells the public that Galactus wants Franklin (Fantastic Four: First Steps)

Relatively early in Fantastic Four: First Steps, the Fantastic Four venture into space to either defeat or negotiate with Galactus before he devours Earth. The mission fails, and during a Press Conference upon their return, Reed Richards, aka Mr. Fantastic, reveals the reason for their failure: Galactus could not be negotiated with because the price to be paid in return for Earth's safety was Reed and Sue Storm's newborn son, Franklin Richards.

The reveal damages the usually positive relationship between the F4 and the general public. On balance, this is not as big a mistake as some of the others on this list. No major damage is done, and Sue is eventually able to smooth things over. Still, this doesn't change the fact that Reed complicated matters unnecessarily. He could have just claimed that Galactus was unwilling to negotiate. There was no real reason to mention Franklin.

As Avengers: Doomsday and Avengers: Secret Wars form a two-part story, it's unlikely that things will go perfectly in Doomsday. We'll likely see another big mistake made.. the question is what it is, and who will make it.