Supernova asks a depowered Superman what Booster Gold is doing during Gold's Dying Moment of Awesome, and Clark admits he's awestruck at Gold's display of heroism. Turns out Supernova IS Booster Gold, and just fished Superman for a compliment.
Doc Magnus is seen working on the Plutonium Man without wearing any sort of protective gear, just normal clothes and a lab coat. Even when it's complete, he just stands in front of it with no protective gear. Being around Plutonium for so long without protection should have given him radiation poisoning.