 FAIR: ... almost everything. This is a comedy animation series, and  while efforts are certainly made to create a vaguely consistent  setting in which mostly consistent characters live and work, the  emphasis is clearly on laughs. Individual episodes must be  consistent within themselves, but rigid continuity between episodes  is unnecessary. Indeed, additional humor has been wrung, during the  life of the show, from the very fact that the episodes are  inconsistent with each other. No further "In one episode they say...  but then in another episode they say..." goofs can be accepted.