Was originally going to be called "Oracle." Oracle was Batman's "Felicity".
On the wall in Felicity's apartment, she has a movie poster from the The Adventures of Robin Hood (1938) starring Errol Flynn.
In the flashback scenes, Felicity is seen wearing an amulet known as the Egyptian Ankh symbol. This symbol is used by the DC character and hero Dr. Fate, who uses the symbol when casting spells, teleporting or shooting energy from his hands. It is also a common symbol worn by high school- and college-aged goths in the 1990s.
When Ray Palmer enters Felicity's apartment he says, "Nice apartment. Lots of space." This was also said by Bruce Wayne and the Joker when they entered Vicky Vale's apartment in Batman (1989).
This episode's villain(s) is a group of radicalist hackers that call themselves "Brother Eye." In DC comics, Brother Eye was actually the name of an A.I. System that Batman had created. (His equivalent to Iron Man's "Jarvis.")