Continuity mistake: Sara's bun changes places on her head during her last dance.
Continuity mistake: When Sara is talking on the phone to her friend from her other school, her friend asks if there are any white guys at her school, and Sara says no there aren't. In the classroom scene and in other shots, you can see a few white guys.
Answer: "N*gro" was the PC term in the 60's. While by no means vulgar, it has mostly fallen out of use and some people are offended by it.
Grumpy Scot