Patrick Sabongui, who plays the street thug, goes on to star in the Arrow spin-off The Flash (2014) as the Central City Police Department's Captain Singh.
Vertigo was the drug that Thea Queen used, and the Count was the nemesis that manufactured the drug and pushed it on the streets. The drug induced, among other things, dizziness. In the comic book series, Count Vertigo was a nemesis for Green Arrow. Count Vertigo's power, which was artificial in nature, was to cause people to become so dizzy that they could not stand. Green Arrow was able to defeat Count Vertigo in the comic even though he too was affected by Count Vertigo's power. He did this by using an arrow that was equipped with a homing device. Though Green Arrow shot wildly, the arrow homed-in on Count Vertigo and rendered him unconscious.
During the court hearing it is revealed that Thea's middle name is Dearden. In the comics, Mia Dearden is the name of the second character to take the mantle of Green Arrow's sidekick Speedy.
When Oliver goes to see the Bravta, Alexi Leonov says "Anatoly Knyazev speaks very highly of you", to which Oliver replies that it is because he saved Anatoly's life. In DC comics, Anatoli Knyazev is a Russian villain called KGBeast. The character appears several times over the course of the series played by David Nykl. The character also appeared in the movie Batman v Superman: Dawn of Justice (2016) played by Callan Mulvey as a thug for Lex Luthor.
The music during the fight scene between Oliver and The Count is the same music used in the show Teen Wolf (2011) which starred Colton Haynes who plays Roy Harper in this Arrow (2012).