When Oliver kills the corrupt cop after breaking loose from his chair, he kills him in the same method and delivers the same line as the first episode of the series; "I'm sorry, but no one can know my secret." (Before snapping his neck.)
Katie Cassidy will reprise her role as Laurel Lance in a flashback sequence to reveal the promise she asked Oliver to keep before she died.
First time in the series where the opening shot of the first episode in the season does not show a POV of Oliver running through a forest. Season 1 and 2 was on the island (Lian Yu), season 3 was a line of trees/bushes alongside a train route, and season 4 was a park near Oliver and Felicity's home. This season it cut straight to Thea at one of Oliver's events as Mayor.
This is the highest rated episode of arrow since late season 4