Clark Kent and Lois Lane, characters from Superman: The Animated Series (1996), can be seen in the background at the park in the scene after the ventriloquist goes up the stairs from the subway into the park.
The establishing shot towards the end of this episode which shows a harbor is actually the exact same shot used toward the beginning of Sins of the Father (1997). Two-Face can be seen on the dock, although he is never seen again throughout this episode.