Code of Silence

"Code of Silence" is the fourteenth episode of the fourth season of Arrow and the eighty-third episode overall.

Synopsis
Oliver and team uncover H.I.V.E.'s plan to take out Team Arrow once and for all. With H.I.V.E.'s next attack imminent, Lance wonders if Donna is safer without him in her life. Meanwhile, with the wedding fast approaching, Oliver begins to feel guilty that he hasn’t told Felicity about his son.

Production
Preparation ran from December 4 until December 14, 2015. The first part of shooting ran from December 15 until December 18, 2015. The second part of shooting ran from January 5 until January 8, 2016.

Trivia

 * This episode introduces the Demolition Team. In the comics they are traditionally enemies to Green Lantern.
 * Oliver tells Curtis Holt that he's "terrific", which is a reference to his comic counterpart's codename, Mister Terrific.