" Treehouse of Horror XII " was directed by Jim Reardon and co-written by Joel H. Cohen , John Frink , Don Payne and Carolyn Omine . It is the twelfth episode of the annual '' Treehouse of Horror '' Halloween specials , and , due to Fox 's contract with Major League Baseball 's World Series , the episode was pushed back to November 6 , 2001 on the Fox network , airing six days after Halloween . As with the rest of the Halloween specials , the episode is considered non-canon and falls outside of the show 's regular continuity . This was the first Halloween special where the writers did not have " scary names " in the credits . This was due to the terrorist attacks on September 11 , after which the staff were " trying to be sensitive " , and , according to producer Ian Maxtone-Graham , the Halloween names would all reference the attacks had they been kept . Mike Scully , who worked as showrunner for the episode , stated that the " scary names " were removed because they had also " turned into shameless plugs " for side projects done by '' The Simpsons '' staff members
terrorist attacks on September 11
September 11 attacks
Treehouse of Horror XII