With the episode setting up a big, season-long mystery, it seems likely this episode of Arrow will be one of the less reference-filled ones of the season.
Why? Simple: if you use specific, familiar characters or concepts, they can be tied back to other characters and concepts to help "solve" the mystery.
So...what did we see?
News 52: “The Debate”
News 52 is on TV all the time in this show, but this episode was a little different.
The talking heads were having a talk about the value of superheroes versus the risk of having the Arrow a target and a magnet for terror attacks like the ones that happened in the season finales of SEason One and Season Two.
That's the kind of thing DC Comics tends to like to do. It's epitomized by the debates about the role of Batman in The Dark Knight Returns, but it's something we've seen again and again in the DC Universe, and also on Smallville.
Vertigo II: Electric Bugaloo
Hey, look! It's the actual Count Vertigo from the comics -- kind of. Werner is the guy, anyway. Not that he actually acts or looks all that much like him, but it does seem like this is the real-deal, long-term Count Vertigo we're going to have on the show.
...And, yeah. The effects of Vertigo are errily similar to the effects of Scarecrow's fear gas in Batman Begins. We talked about that a little earlier.
That Japanese woman, Tatsu Yamashiro, will one day be Katana, a member of Green Arrow's team of Outsiders and a sword-wielding badass.
The guy Felicity meets at the electronics store, and who then pops up trying to take control of Queen Consolidated, is actually a longtime member of the Justice League.
The rebranding of the city that Ray Palmer suggests is actually the name of the city in the comics. "Starling City" was a creation for TV.
The Flash! He crossed over into this episode, setting up the scene in The Flash where Oliver tells him to wear a mask and be a guardian angel to his city.
My tired, New York Comic Con-preparing eyes didn't see them, but a regular commenter below assures me that Ted "Wildcat" Grant and Ferris Air both got shout-outs in the boxing sequence.
Ted is a former boxing champion who became a vigilante in the comics, and also helped to train a number of the best fighters in the DC Comics Universe, including Batman and Black Canary. He's been cast this season and will help train Laurel to become Canary, following in her sister's footsteps and avenging her death.
Ferris is the aircraft company where Hal "Green Lantern" Jordan works, and one of their airstrips is where they tested Barry Allen's super-speed for the first time on the pilot for The Flash last night.
Here are some things that we see often enough that it's hard to consider them special, or particularly hidden...but fans still point them out in the comments enough that we'll list them here.
The episode opens with Oliver tumbling through bushes and over train tracks, following a slow-moving truck heading up 52nd Street. That's a reference to the popular DC series 52 and the DC publishing relaunch called The New 52.
Lyla Michaels, better known as Harbinger, was a key player in the Crisis on Infinite Earths. Here, she is an A.R.G.U.S. agent and Diggle's girlfriend.
News 52 is referenced above.
Amanda Waller is the head of A.R.G.U.S. and responsible for oversight of the Suicide Squad.
Nanda Parbat, where Sara went to be with the League of Assassins, is the fictional place in the comics where Ra's al Ghul trains his assassins...and lots more.