Batman stops King Shark with a canister of Bat-Shark repellent. This is a nod to the Adam West Batman movie when he uses it to fend off a shark clinging to his leg.
While the fight between Batman, Harley Quinn and Poison Ivy was being broadcast, we briefly see Aquaman watching the fight while on the toilet. This harkens back to a joke on The Big Bang Theory (2007) episode The Robotic Manipulation (2010) in which Raj wonders aloud how Aquaman goes to the bathroom. Kaley Cuoco stars on both shows.
Superman's first appearance in the series.