Faith Based Initiative - S6-E10
Other mistake: In the flashback episode where the early days of the first Bartlet campaign are shown, Toby is "teaching" C.J. the proper technique for passing a basketball, something she is not very good at. Yet in this episode, when C.J.'s sexuality is questioned in the news, her history as a star basketball player in high school and college is revealed.
Chosen answer: A really annoying innate lack of sense. My friends and family say the same thing all the time, and I'm endlessly trying to correct them. I think people just don't know any better and (ironically) couldn't care less that they're speaking incorrectly.