Random Most Glaring Unexplained Plot Holes In Marvel Movies (14 items)

(#11) When Does Tony Stark's Arc Reactor Become Removable?

In Iron Man, Tony Stark has to keep an arc reactor in his chest to prevent shrapnel from shredding his heart. But in Iron Man 3, he has the reactor surgically removed without any negative consequences or explanation as to why he couldn't do this before.
(#8) When Does Loki Meet Thanos?

At the end of Thor, Loki is falling through infinite space. He doesn't reappear until The Avengers, when, without explanation, he's hanging out with Thanos. When did these two meet? How did they find each other? How exactly Loki got from point A to point B is never fully explained.
(#7) The Avengers Save The World Repeatedly But Still Get Lectured

In Captain America: Civil War, US Secretary of State Thaddeus Ross claims the Avengers need government oversight, citing the Chitauri invasion of New York that took place in The Avengers and the battle over Washington, DC, in Captain America: The Winter Soldier as reasons the Avengers need to be held in check. He even drops Sokovia into the mix.

Yet, if the Avengers had not intervened, New York would have been invaded and massacred. In fact, the Avengers weren't even a group back then. Also, the attack on Washington came about because of Hydra moles in S.H.I.E.L.D. and the government, not because of the Avengers. And yeah, maybe Tony accidentally created Ultron, but his team stopped the robot from turning a city into a life-exterminating meteor. In other words, the only valid argument for government oversight is the Sokovia destruction by Ultron. That's the only time the Avengers are even indirectly responsible.
(#13) If Odin Can Send Thor To Earth Without The Bifrost Bridge, Why Rebuild It?

The Bifrost Bridge's destruction at the end of Thor prevents the citizens of Asgard from traveling to other worlds. Except during The Avengers, when Thor just appears out of the sky.

Odin apparently can use magic to send Thor to Earth. If Odin has this ability, why is the loss of the Bifrost Bridge such a big deal? Why even rebuild it at all? What's stopping Thor from asking his father for a trip to Earth to visit Jane Foster every weekend?
(#2) Do The Avengers Know That Agent Coulson Is Alive?

Agent Coulson's death in The Avengers helped bring the team together, but now that Coulson is alive, do the Avengers know? Joss Whedon, director of The Avengers and Avengers: Age of Ultron and creator of Agents of S.H.I.E.L.D., considers Coulson to be dead in the movies. But in the show, Coulson's revival is supposedly kept secret from Thor the Avengers. How is that possible?

In S.H.I.E.L.D., Coulson carries out missions with Thor's Asgardian friend Sif, so does she keep that a secret from Thor? After Coulson clears undercover Hydra agents from S.H.I.E.L.D., how do Black Widow, Hawkeye, and Cap not know about him?
(#5) Why Doesn't Tony Stark Make A Suit Out Of Vibranium?

In Iron Man 2, Tony Stark discovers a way to synthesize a new element to use in an overhauled arc reactor, replacing the palladium that is poisoning him. This may be vibranium, though some movie fans claim otherwise.

If Stark made an entirely new element, he'd still have the means to access it. Tony's father Howard Stark found enough vibranium to make Captain America's shield and Tony was aware of Ulysses Klaw's smuggling of the stuff from his arms-dealing days. So if Tony knows how powerful vibranium is, why doesn't he make at least one indestructible suit out of it?