At the end of this episode a title card appears that reads, In Memory of Barry Friedman. Barry was a post production coordinator who passed away suddenly in late August of 2018.
In the DC Comics, Mother is the sole survivor of a small village that was destroyed during a gruesome war. She is a villain who wants to make children stronger by forcing them to endure great tragedy. The character was created by James Tynion IV and Scott Snyder and first appeared in Batman & Robin Eternal #1 (December 2015).
During the Batman & Robin Eternal storyline, two individuals took up the name of Orphan, David Cain and later his daughter Cassandra Cain. During the DC Rebirth, Cassandra was later inducted into Batman and Batwoman's "boot camp" for young vigilantes.
Alex Morf is another MCU-DC crossover actor. In Rabbit in a Snowstorm (2015) he played mob hitman John Healy. Here he plays Sykes and in Bat Girl Magic! (2021) he played Victor Zsasz.