The crossover event for the following year set up the plot for Legends of Tomorrow by introducing viewers to Hawkgirl, Hawkman, and Vandal Savage.
The Justice Society were a major plot point in season 2 of Legends of Tomorrow with one member of the team, Vixen, eventually leaving to join the Legends.
Though viewers were able to meet several members of the JSA, Sandman nor Sandy Hawkins were among them.
The next event promises to be the biggest yet by encompassing all four Arrowverse shows for the first time.