Chloe's text message indicated a "maniac with a boomerang". This could be a reference to 'Captain Boomerang' from the comics, ordinarily a Flash villain, and occasional member of the Suicide Squad.
Carlo Marks, who plays Stephen Swift aka Warrior Angel, previously starred in the season 7 episode Apocalypse as Chloe's Fiancé.
Zatanna calls Clark "Blue" which is in reference to Superman's nickname among Justice Leaguers in the comics. "The Big Blue Boy Scout" Also, in the comics Oliver Queen aka Green Arrow is known to refer to Superman as "Blue" almost exclusively.
This episode contains numerous references to the Star Wars franchise. While in the convention Alec walks past a statue of Yoda and later a statue of C-3PO. Clark and Lois also talk infront of a statue of Palpatine/Darth Sidious. Also, Lois is dressed as a Stormtrooper while at the convention and says a famous quote from Episode 4: "I can't see a thing in this helmet."
The warrior angel comic is a reference to the first Superman comic created by siegel and Shuster, where Superman was a villain. This first draft was also rejected by publishers, so the creators launched it in their own magazine.