There have been many " Easter Eggs" in Arrow. Just a few were Kord Industries, Harley Quinn, and Officer Lance's call sign Delta Charlie 5-2 ( DC 52). Well now we have another upcoming "Easter Egg". Straight from the producers twitter page. Marc Guggenheim tweets a picture of Ferris Air with the caption, " We fly without fear." That is a very awesome Green Lantern reference. It would be awesome if Green Lantern joined the Arrow team, but I am still waiting on Harley to pop up again ( which probably won't happen, super sad face).
Who are you hoping to see next in the Arrow-verse?