10Carol Hasn’t Been Back To Earth
When it was announced that Captain Marvel would be set in the '90s, one of the biggest mysteries was where Carol has been all this time. If she is such a powerful hero who comes from Earth, surely it would have been helpful to have her around when the Chitauri
attacked New York or Ultron almost ended the world.
The movie explains this by having Carol leave Earth to help the Skrulls find a new home planet. It would seem that after leaving, Carol never returned. Therefore, when she appears at Avengers HQ, it is her first time on Earth roughly 25 years.