Continuity mistake: Just before the friends slide, the door behind Rembrandt and Arturo alternates between open and closed between shots.
Continuity mistake: When Serena and Rembrandt go sit on the couch, she hadn't grabbed the champagne glass yet, only reaching for it. But in the next shot it's already up to her to lips.
Chosen answer: Quinn's brother was going to be a recurring character, so "introduced" in this case referred to the actor becoming a semi-regular.
Jean G