During the "Cooperation" rap the Starfires resemble Salt-N-Pepa, the Beast Boys resemble Kris Kross, the Cyborgs resemble LL Cool J with the hair style of Kid 'N Play , and the Robins resemble Vanilla Ice.
During the "Cooperation" rap the Titans from Teen Titans (2003) wear '03 on their shirts while the ones from Teen Titans Go! (2013) have '13 on theirs.
Scott Menville, Tara Strong, Khary Payton, Hynden Walch, Greg Cipes, and Kevin Michael Richardson all did double duty, voicing both the Teen Titans (2003) and Teen Titans Go! (2013) versions of the characters.
The Titans from Teen Titans (2003) mention both the death of Terra and the defeat of Trigon. This clearly places the story as taking place after the end of their series.
Hanging in cages in the Trigons' lair are Mister Mxyzptlk and Hal Jordan's Green Lantern.