Karen's joke that she's "thinking of giving [drinking] up, and moving on to the hard stuff" is a reference to the comics, where Karen did in fact develop a heroin habit.
Madame Gao states that she is returning home to a place "a considerable distance farther" than China. This along with the Iron Fist symbol on the heroin packets points to her originating from K'un-Lun. This is the mystical city hidden in the Tibetan mountains where the Marvel hero Iron Fist was raised.
The dragon symbol on the heroin the Chinese are packing is the symbol of Iron Fist villain Steel Serpent. Iron Fist will be the fourth of the Marvel Netflix shows, to premiere in late 2016.
The book seen behind Ben Urich in his home is "The Power Brokers," by Robert A. Caro. The book tells of the real-life person Robert Moses, frequently described as an inspiration for the character of Wilson Fisk.
The framed newspaper cover that Ben pulls out of his box at the end of the episode references the Battle of New York. This is the battle at the end of The Avengers (2012).