This is the highest rated episode in the entire series.
This is the first episode in which the Machine explicitly identifies Fusco as an asset. He is identified as a secondary asset in the third simulation, when the probability of his survival is calculated.
Finch is using an actual software bug called Shellshock to gain access to the computer system. Shellshock is a family of security bugs in the widely used Unix Bash shell, first disclosed on 24 September 2014.
All super slow motion scenes were filmed with a Weiss camera, also used to film the opening credits.
Scenes in the basement of the stock exchange were filmed in an actual government server farm in Staten Island.