Missing

"Missing" is the twenty-second episode of the fifth season of Arrow, and the one-hundred-fourteenth episode overall.

Synopsis
Black Siren returns to help Chase. Felicity organizes a birthday party for Oliver while Lance is furious after Rene misses the custody hearing for his daughter.

Production
Preparation ran from March 7 until March 15, 2017. Shooting ran from March 16 until March 27, 2017.

Trivia

 * This is the fifth penultimate episode to be named after a Bruce Springsteen song. The song originally appeared on the soundtrack to the 1995 film The Crossing Guard.
 * This episode marks the first appearance of Byron Mann as Yao Fei in 4 years, as he last appeared in Darkness on the Edge of Town.
 * When Diggle and Felicity were in a car and saw Talia al Ghul, Felicity said that she has flashbacks from Isabel Rochev, and when they tried to hit Talia with the car and it didn't work, Felicity mentioned that it worked better with Isabel. This is a reference to Streets of Fire, when Felicity hit Isabel with a van and saved Diggle.
 * Felicity got Oliver's birthday cake from Lord Mesa Bakery, a nod to Lord Mesa, an artist who frequently created art of the Arrowverse. His artwork appears on the cake. Also there is a number 6 on the cake beside the Green Arrow character which signifies the current members of Team Arrow and it also signifies that Arrow will be returning with a new season after the season finale of season 5.
 * This episode marks the return of Manu Bennett as Slade Wilson, as he last appeared in The Return. However, a clip of Bennett's performance was seen in Invasion!
 * Curtis says that he always wanted to see Florence, clarifying that meant the city and not "the woman or her weird machines", referencing the indie rock band Florence + the Machine.
 * Kovar touches Oliver's various scars, causing him to flash back to each of the moments the wounds were inflicted.
 * A scar on his upper right torso from when Yao Fei shot Oliver with an arrow in the first season episode.
 * A scar on his stomach, where Billy Wintergreen stabbed him with a katana in the first season episode.
 * Scars on his back from when Conklin whipped Oliver in the fourth season episode.
 * After a number of their friends have been kidnapped, Felicity likens their situation to a "horror version" of the 1993 film Groundhog Day.
 * This episode marks the first appearance of Malcolm Merlyn in the present storyline of Season 5. He only appeared in flashbacks of Kapiushon, a dream in Invasion! and joined the Legion of Doom during season 2 of DC's Legends of Tomorrow after Schism, which means that this will be a year later for him.
 * Nyssa al Ghul tells Oliver that when she was a little girl her father instructed her to visit Lian Yu and this is where she had found Sara Lance. When Sara Lance had been in the League of Assassins in 1960, as seen in the first season DC's Legends of Tomorrow episode, she told Ra's al Ghul to make sure that Nyssa was near Lian Yu so that they would meet, to keep her timeline intact
 * When Oliver showed Malcolm and Nyssa his progress in tracking Chase's plane, a map of the west coast of the United States appeared, placing Star City in the approximate location of the real-world San Francisco.
 * Oliver receiving help from old enemy Malcolm Merlyn and asking old foe Slade Wilson for help is similar to the The Flash episode that aired that same week when Barry asked Captain Cold for his help too.
 * Malcolm mentions the last time he was down in the Arrowcave he saved Oliver's life, referring to the events of season 4's when he arrived to save Team Arrow from H.I.V.E.
 * Oliver and Thea refer to the last time Thea had a birthday party which was 4 years ago in season 1's.