This marks the beginning of the Season 4 story arc revolving around the mysterious crystalized six-locked chest from the Tree of Harmony.
As of this episode, the Mane Six no longer have the Elements of Harmony due to being given back to the Tree of Harmony.
Friendship Report: Twilight learned despite her new responsibilities in life as a princess, her friendship with everypony will never be broken.
The Twilight-faced scepter given to her by Discord has become popularized across the internet, having been given the name "Twilicane".