Readers of Captain Marvel in the comics know how her cat, Chewie, was an alien called a Flerken and not an Earth cat. While it’s been suspected that Goose in the Captain Marvel movie would also be a Flerken, there was no confirmation on that…until now.
Toys of Goose are starting to appear on shelves, and they confirm that the cat is indeed an alien:
— Peter Porker, Spider-Ham (@samash76082) February 9, 2019
This explains why Nick Fury puts the cat into restraints at some point in the movie.