Chris Wood reprises his role as Kai Parker. He last played this character (though only in archive footage from The Vampire Diaries (2009)) in S2 E4 "Since When Do You Speak Japanese?"
The dress Lizzy is wearing is similar to her (surrogate) mother Caroline's, which was given to her by Hope's father Klaus in "The Vampire Diaries," and loaned to Hope by Lizzy, when she too won Miss Mystic Falls in it.