Eddie is a teenager in his first week at a new job. It is highly unlikely that he would be left in charge of the entire store overnight on his own.
There is no way any of the kids trick or treating would know to dress as school Britney Spears for her song "...Baby One More Time" as the song only release on October 28, 1998 and the music video, for which the outfit is famous, released a month later in November 1998.