Even if you have already filed for an adjustment of status, since your Visa has expired, you no longer have legal permission to remain in the United States (until your AOS application is processed & you get your green card). You can still be stopped and questioned and also be put into removal proceedings, so I would not encourage travel, especially through airports at this time.
PR is a domestic flight. What do you mean when you say that your visa has expired? Are you trying to say that your period of authorized stay in your I-94 has expired? Do yourself a favor and hire an experienced immigration attorney.
Luis A. Guerra, Esq.
Law Office of Luis A. Guerra, PA
Atrium Centre
4801 South University Dr., Suite 252
Fort Lauderdale, FL 33328
(954)434-5800
www.guerralegal.com