When Pop calls Luke Cage Power Man, that is a reference to his name in the comics.
Cottonmouth is selling weapons made by Hammer Industries. Hammer Industries is run by Justin Hammer and was a competitor of Stark Industries. Justin Hammer appeared in Iron Man 2 (2010) and was played by Sam Rockwell. In the Iron Man movies Hammer tech was often depicted as not being all that he claimed it to be. At times his weapons were even known to malfunction.
The "rebound chick" mentioned briefly early in the episode is Jessica Jones.
Pop's list of people who don't pay at his Barbershop include: Muhammad Ali, Nelson Mandela, Richard Roundtree, Michael Jordan, Al Pacino, and Pat Riley. Of the list, Richard Roundtree is the actor who played Shaft (1971), the iconic blacksploitation hero that Luke Cage was inspired from.
Seagate is a real place. However it is not a prison, but a private, gated community located on Coney Island in Brooklyn, New York.