Many people question how Bender successfully guesses the word that simulates the bomb, yet the world isn't blown up and all the crew surrive. During the episode Captain Zapp Brannigan says, "it will detonate the instance the robot unwittingly speaks a certain word." At the end of the episode, when Bender is trying to guess the word, he won't be speaking the word unwittingly. Ergo, the condition required to stimulate the denonation of the bomb won't have been reached. This explains why the bomb didn't explode.