Arrow showrunner Beth Schwartz said that the show’s writers’ were very cognizant of making its 150th episode special for the fans. The episode will be a faux-documentary narrated by Kelsey Grammer, dealing with the rise of vigilantes. [We] came up with the brilliant idea to film it documentary-style, and it allowed us to use all of our favorite characters from past and present in this format, which was something that was really important to us because as you’re hitting such a milestone.