Trivia about Batman: The Dark Knight Returns Part 2. * After The Joker is allowed on his day pass to go on a talk show, the one Dr. Wolper brings him to is called "The David Endochrine Show". This fictional show is meant to spoof Late Night with David Letterman, with the host supposed to parody David Letterman. The actor playing David Endochrine is Conan O'Brien. The character was thus re-designed to appear closer to his voice actor. O'Brien later took over Late Night show after Letterman in 1993. * During the fight between Superman and Batman in crime alley, a framed picture of Christopher Reeve's Superman can briefly be seen in one of the rooms. * Although his name is never specifically said, the character design and voice of The President of the United States is clearly patter