The initial shot of Mr. Freeze's head is done in the style of artist Mike Mignola, who is most famous for his comic book series Hellboy.
Mr. Freeze last appeared in The New Batman Adventures (1997) episode Cold Comfort (1997). It was never explained how his head came to be in the possession of Wayne-Powers. However, Freeze re-appeared in the DCAU-based comic books Batman: Gotham Adventures #5 and Batman Adventures #15. In the latter issue, Freeze's head is retrieved by Warren Powers (Derek Powers's father), head of Powers Technology, keeping it in the belief that it will lead him to the secret of immortality.
First appearance of one of Batman's original enemies in the series. Subsequent ones included Bane, Ra's al Ghul, and the Joker.
Linda Hamilton also appeared in "Chemistry (1998)" as a Stepford Wife-ish woman with whom Bruce falls in love and marries.