Goose And The Tesseract
The first Captain Marvel post-credits scene isn’t so much an easter egg as a preview of what’s to come in Avengers: Endgame. The film’s second credits sequence, though, appears to be a mere extra bit of comedy, but does actually call back to events of MCU past.
The short scene features Goose the cat Flerken cough up the Tesseract onto Fury’s desk, after swallowing it during the climax. This tells us how the future S.H.I.E.L.D. director came to have the Space Stone by the events of The Avengers. Presumably, from this point on he restarts Project P.E.G.A.S.U.S. and continues to study what the Tesseract can do.
What’s more, fans have noticed that this Captain Marvel scene gains another level of foreshadowing when you remember Bruce Banner’s introduction in the 2012 team-up movie. When Black Widow shows him a photo of the Tesseract, Banner sarcastically responds: “What does Fury want me to do? Swallow it?” Well Bruce, based on his experience with Goose, maybe.