Other mistake: When Catwoman scratches Batman's face in the flashback, her fingers and claws stretch comically.
Batman: The Animated Series (1992)
1 other mistake in season 4 - chronological order
Starring: Mark Hamill, Kevin Conroy, Efrem Zimbalist Jr., Loren Lester, Bob Hastings
Genres: Action, Animated, Crime, Drama, Family, Fantasy, Mystery
Continuity mistake: The mud stain on Harvey Dent's suit disappears when he assaults the henchman that kicked the mud on him and then reappears when he is walking away from the scene. (00:04:50 - 00:05:50)
Rupert Thorne: All men have something to hide. The brighter the picture, the darker the negative.
More trivia for Batman: The Animated SeriesMore questions & answers from Batman: The Animated Series
Answer: Because he stole a chemical from his lab.
But Batman knew that with it, Clayface could permanently retain his shape and Clayface desperately wanted to be Matt Hagen again. In a sense, Batman stopped Clayface from becoming human.