The job was not to fly about looking for random lifeless planets, it was to go to a known planet and verify that it was lifeless down to the microscopic level. Either Reliant's navigation was outrageously in error, or whatever orbital shift CA5 underwent moved it into the exact former position of CA6, ignoring whatever debris was left over and the total planet count. Either way, fairly dumb, but OTOH doesn't harm the movie overall, IMO. Who did? Arresting Saddam would have involved a fight to, in and around Baghdad, and probably an extensive manhunt to actually put the grab on him, with a lot of civilian deaths. Then there would be a post-war power void. No one knew exactly how to fill it without adverse consequences, but they knew it would take an extended military commitment. Unlike 2003, though, the GHW Bush administration understood that they didn't have a good post-war plan, so the decision was made to leave Saddam in power after he withdrew from Kuwait.