The town of Blue Valley, Nebraska, which the new family moves to, is also the traditional home of Wally West, the original Kid Flash.
The moving truck seen at the beginning of the episode has Action Movers on its side. The Action part is the logo for Action Comics one of DC comics longest running titles.
While most fans may know of Green Lantern, the one in opening scene isn't Hal Jordan, John Stewart, or the recent ones. The Golden Age Emerald Knight was Alan Scott who was the Green Lantern of the Justice Society. During the series premiere, while he doesn't appear on-screen, Lantern's green energy can be seen across the entire building where they're fighting the Injustice Society.
In the original comics iteration, Sylvester Pemberton was the non-powered teen-aged hero Star-Spangled Kid. He and his adult side-kick Stripesy were founding members of The Seven Soldier of Victory in WW II, but were lost in a time warp. Upon returning to Earth, they joined the All-Star Squadron, and later, the Justice Society. Starman was a separate hero, Ted Knight, who eventually passed on a version of his Cosmic Rod to Sylvester. But Sylvester was never known as Starman.
This marks the fourth live-action appearance of Solomon Grundy, after Legend of the Superheroes (1979), Arrow (2012), and Gotham (2014). Arrow only used his real name, Cyrus Gold, but otherwise depicted him with the Ash White Skin, Super Strength, and Super Durability.