Green Lantern says “You'll have to stop us first, Sinestro” but he says it with Apache Chief's voice
When Green Lantern says “The Super Friends will never be the same without him” his costume is missing revealing his bare shoulders
The Noxium Crystal is clearly large enough to be a handful as seen throughout the episode, but when Luthor fires it at Robin, Lex is not holding anything.
When Robin is killed by the Noxium Crystal, he falls dead near an open warehouse door but when we see his body moments later, there's a solid wall behind him.
The bodies of Samurai and Apache Chief also change positions from the time they are zapped & fall to the time the scene pans over the Super Friends