Marge is shocked to discover what she describes as her "first gray hair". In Secrets of a Successful Marriage (1994) Homer says that Marge has been "gray as a mule" since she was 17 and regularly dyes her hair with blue dye #56, and in the next scene Marge chastises him for revealing this.
In a wide shot showing the audience at the love seminar, Disco Stu is seen in two different places.