 The writers discussed potential ideas . Ronald D. Moore had previously brought back Montgomery Scott for the Star Trek : The Next Generation episode " Relics " and since <unk> was appearing in Voyager , they felt that having a member of the main cast from The Original Series return would be repetitive . Some consideration was given by Moore to sending the DS9 crew to the gangster @-@ type planet visited by Kirk in the episode " A Piece of the Action " . It was René Echevarria who suggested a time @-@ travel episode , which was seen as an expensive proposition . Echevarria , however , pressed for the idea . Moore suggested inserting the DS9 crew into " The Trouble with Tribbles " , suggesting it could resolve the question of why a constant stream of tribbles kept hitting Kirk in the head . 
