"and that leaves 15 minutes unaccounted for."
15 minutes of Kim trying to shove Crystal out the door somewhere.....
Too out of it to go home, too out of it to give another address, too afraid to have Kim call her pimp or BF, too afraid to go to the hospital, too stupid to have her take her to a motel or her sister's house, and Kim too mean to just take her to her own house and let her sleep in the car.