Oliver Queen and Felicity travel to Hub City which is the birthplace of The Question in the comics.
When Diggle warns Team Arrow that "Genesis is coming", Felicity quips, "I doubt it. Phil Collins said they'd never tour again." This is a reference to the English rock band Genesis, of which Phil Collins was a drummer and singer.
The title refers to the project which is the endgame of H.I.V.E. and Damien Darhk.
This is the only episode of season 4 that has no flashbacks at all, unlike the past three seasons which all have an episode focusing primarily on flashbacks.