Beacon of Hope

"Beacon of Hope" is the seventeenth episode of the fourth season of Arrow, and the eighty-sixth episode overall. It aired on March 30, 2016.

Synopsis
Brie Larvan breaks out of jail and turns up at Palmer Tech threatening to kill everyone unless she gets the bio-chip that is implanted in Felicity's spine. When Oliver realizes that Felicity, Thea and Donna are trapped in Palmer Tech with everyone else, he looks to a surprising ally to help Team Arrow save the day.

Production
Preparation ran from January 21 until January 29, 2016. Shooting began on February 1 and ran until February 11, 2016.

Behind the scenes

 * After Laurel sidesteps around using Felicity's name, Oliver claims that she's "not Voldemort", a reference to the main antagonist of the Harry Potter series.
 * Thea additionally makes fun of Oliver for actually having knowledge of Harry Potter. He claims to have read a few of the books, and is surprised that there are films.
 * When Curtis sees the Arrowcave, he exclaims "holy frak", a reference to an expletive popularized by the Battlestar Galactica franchise.
 * Curtis compares the robotic bees hitting critical mass to "John Hurt in Alien", referencing the actor's character in the 1979 film, Gilbert Kane, whose head explodes.
 * Curtis asks Laurel to use her Canary Cry by giving it "the full Mariah Carey".
 * When Donna sees the secret elevator in the Palmer Technologies building, she likens it to the 2002 Jodie Foster film, Panic Room.
 * Brie Larvan mentions her "favorite scene from My Girl", likely referencing a scene in which the character Thomas J. Sennett is fatally stung by a bee.
 * The episode's title is mentioned a number of times later in the episode, referencing Team Arrow's need to be a beacon of hope for others, as no one else is.
 * Felicity reminds Thea that they are in a "Die Hard movie with bees", referencing the film series.
 * After Curtis comes up with the idea to upload a virus to the collective of bees, Lance likens it to the 1986 film Independence Day, in which the characters upload a virus to the alien mothership, allowing them to implant a nuclear bomb (effectively decimating the enemy).
 * Curtis punnily calls Larvan "Bea Arthur", a 1970s actress.
 * When Paul goes to heat up soup for Curtis, he describes it as "terrific", referencing his comic book alter ego Mr. Terrific.