A reference is made to the Titans having previously used one of Deathstroke's children against him. This is clearly a reference to Joseph Wilson, a.k.a. Jericho, who has been a member of the Titans in the comics and who was briefly seen in the previous episode.
Just before Gar and Rose have their conversation about cereal, illuminated in the hallway behind them, there is a Greek helmet on display that looks notably like the Helmet of Fate.