Doctor Madison Gray, the person mentioned toward the end of the episode, is a serial killer on Hawaii Five-0 (2010). Prior to the mention of her in this episode of this series, she last appeared in the "Hawaii Five-0" episode Hu a'e ke ahi lanakila a Kamaile (season seven, episode four).
The person that the killer was in contact with in Hawaii, Doctor Madison Gray was a psychiatrist in a Hawaii Five-O story arc at the beginning of season seven. Dr. Gray manipulated killers to kill. The primary piece of evidence in the murders was a chess piece. Dr. Great eluded capture and left Hawaii.
Jack mentions a "buddy" on Oahu in a "task force", meaning the 5-0 task force putting this show in the same universe with Hawaii Five-0 (2010), NCIS: Los Angeles (2009) and Scorpion (2014).
Instead of Matty, MacGyver initially calls her "Patty" in the beginning.