Aren't they just the worst things ever?
All it takes is for one tiny detail to be out of place and all of a sudden an entire movie falls to pieces faster than you can say "retcon".
Great movies afflicted by this terrible curse number in their hundreds, but some of them get a chance to redeem themselves.
How? Through the magic of a sequel, of course!
A new instalment in a franchise is not only a great way to further a story, develop characters, and make more money (the most important thing of all), it's also a chance to fix the mistakes made by a previous film.
That's exactly what happened with this lot here.
They all had to deal with the problems caused by their older siblings, mending the fences they left behind without damaging their own output in the process. Some only needed to make minor tweaks, whilst others needed to do way more heavy lifting to ensure that their plots were watertight against even the most anal of pedants.
Sequels aren't always a bad thing, especially not if you're a fan of continuity.
8. The Tesseract - Captain Marvel
During the first Avengers movie, the Tesseract was a pretty big deal.
We'd later learn that it was home to the Space Stone, one of the six most important MacGuffins in the universe, but at the time it was just a badass cube that caused a lot of trouble.
The superheroes get pretty angsty with Nick Fury when they find out that he wants the object to build weapons, but they failed to ask a pretty important question.
We know that Howard Stark fished the Tesseract out of the ocean whilst looking for Captain America. So, why did it take S.H.I.E.L.D until the early 21st Century to finally do something with this all-powerful energy source?
The answer to that came in 2019's Captain Marvel.
We meet ol' Tessie once again, this time in the year 1989. It's being looked at by Dr. Wendy Lawson, who is actually a Kree named Mar-Vell in disguise. She's been using the cube to try and create lightspeed travel to help the Skrulls flee her people's devastating war with them.
So there you have it, the Tesseract was being worked on all this time, just not by S.H.I.E.L.D.
Also, it got swallowed by a cat.