The only time the Far Universe location was called the Diamond Galaxy instead of the Dinubian Galaxy. (They may mean the same thing since "Dinubian" is similar to the words from which "diamond" is derived.
First appearances of Princess Allura and Coran.
At the end of the first of episode, the ship that the space explorers escaped in is being pulled towards the Castle of Lions by a beam coming from the Lion statue. However, at the start of this episode, the beam is not mentioned. They just crash the ship, and head to the castle on foot.