The character of Felicity Smoak is Firestorm's stepmother in the comics.
The character of Kate Spencer is better known in the comics as Manhunter.
Laurel's black, more laid-back co-worker is named Joanna. In the comics, Joanna Pierce is a lawyer, is the niece of Black Lightning, briefly becomes involved with Oliver Queen, and is murdered by Constantine Drakon.
Dinah "Laurel" Lance works for a legal aid group called CNRI ("Canary").
In most of his appearances, Roy Harper is seen wearing a red hoodie - as in a casual red version of what Oliver wears. Roy Harper went by Red Arrow for a while in the DC universe.
Yao Fei is the real name of Accomplished Perfect Physician of the Great Ten.
Canary's costume doesn't use her signature fishnets, although there is a glossy criss-crossing pattern over her pants.
The second season introduces the news network Channel 52, which appears as a short strip in the back of New 52 books as a way to show larger events happening in the DCU that month.
Dr. Ivo is the name of the nanotech scientist from the Justice League that built AMAZO, a robot capable of copying the superpowers of metahumans. Here, The Amazo is the name of Dr. Ivo's ship.
After Detective Lance's demotion in season two, the code he uses to call things in is Delta Charlie 52, aka DC 52.
While the city is called "Starling City" and not "Star City", on a few occasions we see a newspaper called "The Star", and the city's slogan is "Starling City is a Star City!" The season three premiere has Ray Palmer propose a plan to restore Starling City and rebrand it as Star City.
Which later indeed happens in season four.
John Diggle's brother is named Andy. Andy Diggle was one of the writers of the Green Arrow comics.
In the early seasons, Oliver was known as "the Vigilante", which is the name of several characters in DC comics.
Mirakuru is another way to say Miraclo, the miracle vitamin that Hourman uses to give himself various powers for one hour at a time.
In the pilot:
Oliver calls his sister Thea "Speedy". "Speedy" also happens to have a bit of a drug problem.
There's a reference to Grell Street. Mike Grell reinvented Green Arrow in The Dark Age of Comic Books. Season 1 of Arrow owes a lot to Grell's version, who used regular arrows, fought non-costumed criminals, and didn't use the name Green Arrow if he could avoid it.
In Episode 3:
The land of Markovia is mentioned. It is the home of Brion and Tara Markov, better known as Geo-Force of The Outsiders and Terra of the Teen Titans in the DC Universe.
Big Belly Burger is an established chain from the DCU with its first appearance coming back in 1988 with Adventures of Superman issue #441.
The poison used by Deadshot is called Curare much like the assassin from Batman Beyond.
In Episode Four
Oliver mentions Blüdhaven, the city where Nightwing makes his home.
The Starling City prison is called Iron Heights, which is where The Flash villains are usually locked up in the comics.
In Episode 5
Oliver's mugshot number is 73 1941. Green Arrow debuted in More Fun Comics #73 in 1941.
Laurel jokes about "those horrible fishnets" she wore one Halloween.
In episode 6:
The bank-robbing family wear masks with a playing card motif, a reference to The Royal Flush Gang.
References are made to Keystone City (home of the Flash) and Coast City (home of Green Lantern).
Broomes is a reference to John Broome, prolific writer from DC Comics Silver Age.
Stagg is a reference to Simon Stagg, a known businessman in the DC Universe and the unwitting creator of Metamorpho.
In episode 8:
Huntress wanting her costume in purple. It serves no purpose other than this since barely any purple is actually on her costume. Though the lining of her trench coat is dark purple, and she's give a shot that specifically highlights the purple..
Oliver's penchant for super-spicy food pops up near the end.
In "Trust, But Verify":
Black Hawk Squad Protection Group is reference to the Blackhawks; Ted Gaynor is in reference to Lt. Theodore Gaynor, a short-term member of the team introduced in the 1980s series.
Malcolm Merlyn reveals that Tommy used to have a dog named Arthur after the legendary king. Malcolm's comic counterpart is Arthur King aka Merlyn.
The drug on the scene is called Vertigo, a reference to Count Vertigo. To really drive it home, the maker of the drug is called the Count. His identity as a mythology gag is dropped altogether upon his return, when he actually calls himself Count Vertigo.
During her preliminary hearing, Thea's full name is given as Thea Dearden Queen, and her nickname is Speedy. In the comics, Mia Dearden is a prostitute that becomes Green Arrow's sidekick, the second Speedy.
Also, it is mentioned that Oliver saved one Anatoli Knyazev (which led to his becoming a Captain of the Bratva). In the comics, this gentleman is also known as the KGBeast.
The Hood meets his civilian contacts on top of the Winick Building. Judd Winick is a prominent writer of Green Arrow comics.
A newspaper headline refers to Wolfman and Perez. This is a nod to the two creators of Slade Wilson, a.k.a. Deathstroke.
In "The Odyssey":
Slade mentions a son named Joe ("Jericho" in The DCU) and that his partner is Billy Wintergreen, Deathstroke's butler in The DCU.
In "Dead to Rights", Laurel remarks on the canary her father bought for her sister Sara. And if you look closely, it's a black canary.
Also, Malcolm Merlyn received his training in Nanda Parbat, a secluded Himalayan mystic retreat in the DCU similar to Shangri-La.
The apartment Deadshot initially goes to drink his sorrows away is the Blüdhaven apartments.
China White was wears a white dress in the episode, evoking her status in the comics.
Helena's stripper wear seems to look an awful lot like her costume in the comics merged with that of Dinah's/Laurel's. As she leaves the scene, she wears a Badass Longcoat over the stripper attire, invoking the Civvie Spandex of Huntress in the short-lived Birds of Prey (2002) TV series.
Also, Roy seemed very averse to getting injected with a needle. Maybe there's a reason for that... Comic book Roy is known to have been a ex-heroin user who has.
McKenna's sister lives in Coast City...
Laurel's mother says, "Gotta get going to the airport. That red-eye to Central City. Should be home in a Flash."
Roy keeps the flechette that Oliver used to save him. It may also double as foreshadowing. Hell, the lights in the club even turn red, and thus the arrow looks red. Again, Roy Harper once went by Red Arrow in the comics.
In "The Undertaking":
The Markov device is mentioned. It's an Earthquake Machine, reflecting the powers of the Markovs (Geo-Force and Terra) in the DCU. It was built by Dr Brion Markov, the secret identity of Geo-Force.
Ted Kord, the second Blue Beetle, is name-dropped in a flashback.
Barry Allen comments on how dumb it is to keep certain chemicals next to each other, shortly before a thunderclap can be heard in the background, alluding to Barry's comic book origin.
In the same episode, Barry reveals that his mother was killed by a "blur" with superhuman speed, alluding to Professor Zoom, the Flash's Evil Counterpart and Arch-Enemy.
In "Three Ghosts":
Ollie trashing his own hideout by fighting the "long-dead" Slade who turns out to be a hallucination is taken from an episode of Teen Titans.
An anti-government group known as "The Movement" is mentioned at one point.
In "Blast Radius":
One of the papers on Sebastian Blood's desk contains the name "Saint Walker", the first recruit of the Blue Lantern Corps in DC Comics continuity. In the show's continuity, "Saint Walker's" is a hospital.
In "Heir To The Demon":
Nyssa Al-Ghul uses Nyssa Raatko as an alias, her actual surname in the comics.
After failing to foil her mother's kidnapping, The Canary screams in frustration and her scream is emphasized on-screen, obviously alluding to the Canary Cry.
Dinah Drake Lance's outfit in this episode is mostly black and a navy blue jacket, alluding to Black Canary's costume.
There are references to the Ostrander Suite and the corner of 5th and Giffen. John Ostrander was the creator of the Suicide Squad comic, and Keith Giffen had a notable run on the title. And Shrapnel's Restraint Collar is activated with the code BATB-25 - the original version of the Suicide Squad first appeared in The Brave and the Bold #25.
Harley Quinn is in the prison with the other Suicide Squad members. In the New 52, she is a member of the team. Although not named, the high-pitched voice (actually Tara Strong, in a Role Reprise from several media adaptations), the fact that she calls herself a "trained therapist", the blonde pigtails, and the people she's with at the time make it obvious who she's supposed to be.
The DC fictional countries of Kahndaq and Qurac get name-checked, and the mission takes place in Markovia.
Caitlin Snow and Cisco Ramon use a weapon designed by Arthur Light to fend off Slade. It's mentioned that Light was fired from STAR Labs for being "a psycho".
Cisco, upon seeing Slade, asks if Caitlin is getting "Bad vibes" from him. In the Justice League comics, Vibe is the superhero Code Name Cisco ends up taking after getting powers.
Cisco also tells Caitlin that he "makes [his] own cool". In the comics, Caitlin Snow becomes Killer Frost.
The episode is based off of one. In the comics, Deathstroke really did enter an animalistic rage whenever his Healing Factor healed fatal injuries.
In "City of Blood":
When the city is attacked by Mirakuru-charged criminals in Deathstroke masks, Isabel Rochev appears in a version with the colours reversed and an open mouth area; the same design as Rose Wilson/Ravager III in the comics.
Monument Point, the nearest military base to Starling, is named after a town in Justice Society of America storyline "Supertown", written by Arrow showrunner Marc Guggenheim.
In the Season 3 premiere, "The Calm":
Laurel refers to her and Oliver as 'business partners' because of how they now collaborate to fight crime in Starling. They literally were business partners for a time in the comics, and ran a flower shop together.
Ray Palmer suggests renaming Starling City into "Star City", its name in the comics.
Oliver's association with Amanda Waller and ARGUS in the flashbacks may be a subtle reference to how he was a member of the ARGUS-sponsored 'Justice League of America' team in the New 52 universe.
Felicity says she always envisioned Sarah Lance as an invincible "Amazonian warrior."
The same episode briefly mentions a street named "Lemire."
We learn that Thea has been living under the alias 'Mia'. Mia Dearden was the name of the second Speedy in the comics. (Then again, Thea Dearden Queen was always more or less an Expy for Mia Dearden).
Felicity's new executive assistant at Queen Consolidated is named Gerry Conway.
Laurel questioned Ted Grant about a pupil of his named Tom Bronsan. Tom Bronsan is the name of Grant's son in the comics, who himself later assumed the identity of Wildcat.
Jansen s named after Conner Hawke's sensei in the comics.
In "The Secret Origin of Felicity Smoak":
Cooper's shirt has Starro on it, in the famous pose from the cover of The Brave and the Bold Vol. 1 #28.
Felicity's goth get-up in college is strongly reminiscent of Death from The Sandman, complete with ankh necklace.
Oliver mispronounces Chien Na-Wei's name as 'China White', the name she is known by in the comics.
Oliver spends some time fighting a former vigilante, now a mixed martial arts instructor. Oliver puts an end to the fight by jamming an arrow into a boxing glove and punching his opponent with it, recreating one of the comic incarnation's most frequently used trick arrows.
Another street name: Ted Grant's gym is on the corner of 9th and Hasen. Irwin Hasen was the co-creator of Wildcat.
In "Draw Back Your Bow":
Carrie Cutter's hideout is in a florist's shop named Sherwood Florist, which is also the name of the florist shop Oliver and (Dinah) Laurel ran together in the comics during Mike Grell's run.
In "Brave and the Bold":
Roy's escrima sticks aren't just a nod to his pal Nightwing but also to his role as the drummer of the Titan's band.
Captain Lance mistakenly calls Barry 'Bart Allen'.
When Lyla asks Oliver if things are alright between him and "Speedy," (referring to the Flash) he assumes she's talking about Roy. Speedy was Roy's first costumed name when operating as Oliver's sidekick in the comics.
Thea reads a novel by Brad Meltzer, who's also a comic book writer and had a six issue run on Green Arrow in 2002.
A news report refers to Arsenal as 'Red Arrow', one of Roy's other code-names in the comics. Incidentally, in the comics, Roy took the name Red Arrow when he took Oliver's place on the Justice League, much like how, on the show he is currently taking Oliver's place as the resident vigilante-archer owing to the latter's 'death'.
The episode focuses on Roy's imprisonment. In Young Justice 'Broken Arrow' was Roy's Trigger Phrase to activate his brainwashing by The Light.
Ra's subjects Oliver to vapors from an ancient herb as part of his initiation into the League...much like what was done to Bruce Wayne in Batman Begins. Also from that film is the idea of the protagonist having to participate in the destruction of his city upon joining the League, though the reasons are very different in the two cases (In Begins, Bruce must destroy Gotham because its the League's mission, whereas on the show, Oliver must destroy Starling as part of his initiation). The use of a biological weapon to do so is also common to both stories.
The idea of Ra's al Ghul's heir having to marry his daughter is also an iconic aspect of the Batman-Ra's al Ghul story, with Oliver taking the place of Bruce, and Nyssa taking the place of Talia here.
In "This is Your Sword"
Roy gave ''a lot to the table:
He uses the alias Jason. In the New 52 comics, Roy and Jason Todd are currently partners.
Tatsu is wearing the same mask as her comic book counterpart.
In "Bratva" Rene repeatedly refers to Lance as "Hoss". Hoss is the nickname of one Harry Dresden, who was also played by Paul Blackthorne
In "Deathstroke Returns"
Nylander calls Slade "the Terminator" and he replies he hasn't heard that nickname in a while. His comicbook counterpart was originally "Deathstroke the Terminator" before a certain movie series meant they had to write around trademarks.
The terrorist organisation that supposedly kidnapped Joe Wilson is called the Jackals. In the comics, Joey was mute because his throat was cut by Deathstroke's ex partner Bill Walsh, who had become a terrorist called the Jackal.
In "Promises Kept"
Following from the above, there's a number of points where there's a blade at Joe's throat, although it never actually happens.
In the flashbacks, the prototype of the new (ie current) Deathstroke suit is black and white rather than black and orange, resembling Grant Wilson's Ravager costume in the comics.
In "The Thanatos Guild", when Roy briefly rejoins the team but doesn't have a costume, he wears a baseball cap on the mission. A baseball cap is part of New 52 Arsenal's costume in the comics.
"Life Sentence" ends with Oliver being sentenced to imprisonment in a supermax prison called Slabside Penitentiary, a reference to the long-abandoned Green Arrow movie Supermax. In the comics "The Slab" is yet another Extranormal Prison, first appearing in Green Lantern Vol 3 #90 and playing a major role in the Crisis CrossoverJoker's Last Laugh.
In "Inmate 4587". Felicity is working at a coffee shop called Radu's. Radu's was a major location in the Kyle Rayner Green Lantern comic.
In "Elseworlds Part 2":
Joe Wilson is now calling himself Kane Wolfman. The Kane is his mother's maiden name, but the Wolfman comes from his creator, Marv Wolfman.
When the heroes arrive in Gotham City, their location is given as the corner of Nolan and Burton.
Earth-90 Flash is surprised Diggle isn't wearing a ring, suggesting that on his Earth, Diggle's counterpart is a Green Lantern. This is also a Fandom Nod to a popular theory that Diggle is the Arrrowverse version of John Stewart.