Hillary Horan, the brunette always seen playing the drums, has her name mentioned as a graduate during the diploma sequence. Horan does not appear in the episode. When Horan's name is called out, actress Sally Hightower is the one who gets up. Previously in the episode, however, Hightower is clearly identified as "Sally Hightower".
Actress Sally Hightower is called "Sally Hightower" at the graduation ceremony. However, her character name, as given in the on-screen credits for part 1 of this episode, is "Sylvia".