"Smidt Park," where the final battle took place, is named after Chandler Smidt, one of the writers. It took several takes for the actors to get the pronunciation right.
Kara and Nia's conversation about living with the consequences of mistakes mirrors Barry Allen's conversation with his daughter Nora in Chandler Smidt when they learn that, while in prison in the future, his nemesis, Eobard Thawne, has been subtly manipulating her in order to facilitate his escape from death row.
When Mxy tells the Super Friends about Nxyly's history, the melody of his song is Gloria Gaynor's "I Will Survive."
Emmanuelle Vaugier was in Smallville (2001), which is based on Clark Kent becoming Superman, Supergirl's cousin.