In a scene, at the begining of the movie, Dr. Strange was picking up some cool medical cases. One of these cases was an USAF officer who had an accident. Some people speculated it was a reference to Captain Marvel.
Ok, it could be just a fanboy theory or I am wrong again and just imagined this scene (just like the time I saw Patrick Stewart hugging two pugs in a scene of Dune, when there was only one dog).