This episode marks the first time Pikachu has ever been scanned in the Pokédex, despite having been one of the lead characters since the first episode. This episode also confirms that Pikachu, despite always staying on Ash's shoulder, was already "marked" by a Poké Ball as Dawn's attempt to capture him fails.
To date, this is the only episode in the anime in which Pikachu isn't with Ash at any point of the episode. This is also the only time that Pikachu isn't present when Ash obtains a new Pokémon, a fact noted by Ash himself.
This episode marks the first appearance of Paul, though his character will be fully introduced in the following episode.
Despite Professor Oak calling the Sinnoh region an island in End of a Journey, and Then the Start of a Journey! (2006), Brock somehow manages to get all the way there via truck. However, it is still possible that Brock rode the truck while it was on a sea vessel.
In the English dub, the title card music comes from seasons one through eight, when 4Kids Entertainment still dubbed Pokémon. This marks the last episode (and the only episode during The Pokémon Company International era) where the original title card music was used in the dub.