Continuity mistake: In the season five episode Triangle, Anya says she has never driven before, but in Graduation Day part one she tells Xander she has her car right outside. (00:22:50)
Visible crew/equipment: In the final scene in the Magic Box where Buffy cries, in several shots of Buffy you can see, in the right of the shot, the sleeve of a white shirt, which none of the characters are wearing.
Chosen answer: "So goes the nation" seems to have been used on many occasions, with various different US states in the "As .... goes" section. Most commonly it seems to be California that's considered to lead the way, but probably most other states have appeared in the lead role at some point or another. Other things have also been used - no less a person that Pope John Paul II said "As the family goes, so goes the nation...". The origin of the quote format is unclear - in US politics it goes back into the 19th century, when it was Maine that held the title spot, but, while no definitive origin is known, it seems highly likely that it goes back considerably further than that.
Tailkinker ★