Black Siren resurfaces to advance her mysterious backer's agenda. Meanwhile Alena comes back for Felicity's help.
- Actor Allusion: Not the first time Michael Emerson played a computer genius.
- Affably Evil: Cayden James, despite being a ruthless hacker and possible Omnicidal Maniac, proves to be a soft-spoken and polite man, addressing Black Siren and Felicity as "Ms. Lance" and "Ms. Smoak" respectively, and even ordering his men to be "as humane as possible" when they're about to execute Felicity and Alena. He also raises an objection (albeit a somewhat half-hearted one) when Black Siren unnecessarily kills a security guard.
- Ambiguous Situation: Since Cayden later admits that Felicity preventing the destruction of the Internet was part of his plan all along, it's left unclear if he actually did snap while in A.R.G.U.S. custody, particularly as he at least seems perfectly rational throughout the episode.
- Arc Welding: This episode reveals that Black Siren and Helix work together, combining two powerful enemies into one.
- Ask a Stupid Question...: Felicity lashes out at John when he asks her if everything is ok, as it obviously isn't after she just found out that she is responsible for a dangerous criminal on the loose.
- Bait-and-Switch: We see Black Siren conversing with a blonde man played by Tobias Jelinek, who the audience would be wise to assume is Cayden James...until the latter is later revealed to be played by Michael Emerson. According to Word of God, this misdirect was intentional.
- Be All My Sins Remembered: Felicity's work with Helix comes back to haunt her.
- Being Tortured Makes You Evil: Being held indefinitely in solitary confinement for months on end is understandably not good for one's sanity, as we see with Cayden James.
- The Bus Came Back: Alena comes back after Helix left town last season.
- Call-Back: Felicity and Oliver remember their first date 3 years ago, where the second Count Vertigo blew up the restaurant they were dining in with a rocket launcher.
- Confusing Multiple Negatives: Lampshaded by Curtis:Rene: Star City stands at 70% against the anti-vigilante legislation.Curtis: That's 70% for us, accounting for the double negative you just used?
- Create Your Own Villain: By illegally imprisoning Cayden James under inhumane conditions, they turned him from a hacktivist to a straight-up global-scale terrorist.
- Damn You, Muscle Memory!: After the team is back from their mission, Oliver falls back into old habbits by telling them what to do next, only to remember that he isn't the boss anymore.
- Depraved Bisexual: Laurel flirts with each victim, men and women alike, before she kills them and remarked about her third victim that she was so pretty, that she couldn't let go of her until she was truly dead.
- Even Evil Has Loved Ones: Or had, at least. Black Siren responds to a security guards pleas that he has a wife and children with a bitter "I had a family once, too". Whether "had" in this case means that they're dead (she previously said that Earth-2's Oliver is dead) or is just a reference to her being trapped on Earth-1 is unclear.
- Even Evil Has Standards: Downplayed; Cayden James doesn't quite approve of Black Siren's violent methods, but he doesn't raise any particularly strong objections to them.
- Everything Is Online: Discussed, and to a far greater degree than in real life. Apparently in the Arrowverse, the level of dependence on the internet reaches that of the darkest Y2K scenarios, with hospitals and airplanes being deadly compromised if the internet is down.
- Faux Affably Evil: Black Siren plays up the charm when interacting with her victims, whom she then ruthlessly murders. Adding to how vicious the act is, it's later revealed that killing them wasn't even necessary; all she needed was their fingerprints, but she killed them anyway, on the reasoning that a dead body is better than a living witness.
- Four Eyes, Zero Soul: Cayden James could almost pass as the brother of William Tockman, being similarly creepy and villainous while wearing glasses.
- Girl on Girl Is Hot: Rene ponders out loud about whether or not Black Siren seduced a female victim the same way she did a male one. He claims it's a reasonable question, relevant to the investigation. Dinah, unsurprisingly, rolls her eyes at him.
- Had to Come to Prison to Be a Crook: According to Alena, Cayden's moral compass was much like hers prior to being captured and detained by A.R.G.U.S. for months on end, after which he became much, much nastier.
- Heel–Face Turn: Alena is horrified by Cayden James' plan and goes to Felicity for help in stopping him.
- It's All My Fault: Felicity is extremely disturbed by the fact that she helped breaking Cayden James out of prison.
- Jumping Off the Slippery Slope: Cayden James snapped during his time in custody. He went from being a hackivist to Omnicidal Maniac.
- Kick the Dog: Black Siren murders a security guard while he begs for mercy. Even Cayden admits that it wasn't necessary.
- Mood Killer: Slade calls Oliver just when he and Felicity are starting to get intimate.
- Must Make Amends: Felicity thinks stoping James is her sole responsibility since she helped free him.
- Nice Job Breaking It, Hero:
- Felicity helping to free Cayden James comes back to haunt her in this episode. To her credit, she admits that she was wrong to both Oliver and John.
- Oliver rushing in and beating up a backdoor-dealer and his men, thinking that Felicty and Alena were in trouble when in reality they were trying to purchase something from him.
- No Name Given: The henchman of Cayden who is played by Tobias Jelinek is not named; even Wendy Mericle just says that the writers are calling him "Boots" for now, implying his real name may be revealed later.
- Nothing Personal: Cayden outright tells Felicity that he just considers her unfortunate collateral damage.
- Not Named in Opening Credits: Michael Emerson isn't listed in the opening credits, to keep his role as Cayden James a surprise.
- Oh, Crap!: Felicity when she sees Black Siren's reflection in a computer monitor.
- One-Steve Limit: Averted Black Siren uses "Dinah" while sizing up one of her victims.
- Redeeming Replacement: Alena convinces Felicity to appropriate Helix's name for her and Curtis' new company in the hopes of doing more good with the name than the hacktivist group did.
- The Reveal: Who is Black Siren's mysterious backer? Cayden James, leader of Helix.
- Sequel Hook: The episode ends with Oliver getting a call from Slade for help.
- Swapped Roles: As the title indicates, this is the case with Oliver and Felicity. Throughout the episode, Oliver encourages and cheers up Felicity, and during the mission, he is even on the com giving her direction in the field.
- Take That, Audience!: Again Black Siren does a lot of heinous actions; this time killing people for her backer just to remind the audience, she's a villain not Earth-1 Laurel.
- Two Lines, No Waiting: Turns out that Felicity's subplot is connected to Team Arrow tracking Black Siren.
- Unwitting Pawn: Felicity is played like a fiddle by Cayden James. He never wanted to destroy the Internet, he just wanted to upload something on to the net. And why take down the firewall himself, when Felicity could've done it for him? With her digital fingerprints all over the scene making her the perfect patsy.
