 " Underneath " marked the directorial debut of Shiban , who had been a writer for the series for several seasons . Reportedly , the episode contained " so many problems " that the Fox executives nearly refused to allow the finished product to air . At the last minute , however , they relented , and allowed the episode to be aired later on in the season , several weeks after its intended air date . Shiban originally wanted to film the sewer scenes in Los Angeles ' actual sewer system , but due to the events of September 11 , a sewer mock @-@ up was built on Stage 11 at the Fox studios . 
