After a man is mysteriously murdered in a park, Castle and Beckett team up with a competitive, high-powered female detective from Hong Kong, who has information about the victim. But as Beckett digs deeper into the case, she realizes neither her Hong Kong colleague nor the victim may be quite who they seem.
Detective Zhang identifies Michael Glassman via his device's unique MAC address. While it is true that every network adapter in any network capable device has a unique MAC address, it could not be directly used to identify someone.
There is no database linking them to their owners as the devices can be bought off the shelf without need for registration.
The MAC address of a device is only transmitted to the network it is directly connected to (e.g. the wifi router), not beyond that.
Michael Glassman's "MAC address" is listed as "297.465.172.1804.67" which is not a valid form of MAC address which looks more like "00:14:A5:41:61:6B"
It is revealed that Beckett had zits as a teenager.
Detective Zhang life is somewhat mirrors Beckett's previous life where she too used to put her job in front of people who really mattered.