
That's right: a guy known for playing The Ditz is the lead.
Playing Against Type: Diedrich Bader as Batman. The main plot doesn't actually take place during Halloween, but it might as well have been considering the dark atmosphere of the episode. Out of Holiday Episode: Downplayed in Season 1 "Trials of the Demon!", the episode starts with a Batman Cold Open that takes place during Halloween, but the episode first aired during March.
In "Chill of the Night!", Two-Face was briefly reprised by his Batman: The Animated Series actor Richard Moll as opposed to his regular voice actor on the show, James Remar. Thomas and Martha Wayne also underwent this: before they were voiced by Adam West and Julie Newmar in "Chill of the Night!", Thomas was voiced by Corey Burton in "Invasion of the Secret Santas!" and by Greg Ellis in "Dawn of the Deadman" and Martha by Pat Musick in the latter episode. While she was silent in the teaser for "Duel of the Double Crossers!", she was voiced by Kim Mai Guest in "Inside the Outsiders!" The weird thing is that her first appearance features a normal American accent, while she gets a Japanese one in her second. In Katana's debut appearance, her few lines were voiced by Vyvam Pham. Subverted in practice - as heard in both "Mayhem of the Music Meister" and this very episode, Canary's singing voice works just fine (no problems from abusing her vocal cords with that "canary cry" of hers, it seems) - but then that's Catwoman for you. However, Black Canary's voice actress, Grey DeLisle, is a Grammy-winning professional singer. Irony as She Is Cast: The episode "The Mask of Matches Malone!" features a scene where Catwoman jokingly suggests that Black Canary being gagged by the bad guys is a good thing as they no longer have to listen to her terrible singing, much to Canary's displeasure.
Superman got his first appearance in the episode "Battle of the Superheroes!".
She and fellow former exile Superman were seen from behind in the Cold Open to "Sidekicks Assemble!". Played with in "Mayhem of the Music Meister!" where a picture of Wonder Woman is seen in Music Meister's Death Trap room, only to have her face obscured by other concert stickers so that you could only see her hair and trademark tiara.