- Actor Allusion: Billy Bob Thompson (the voice actor of Cross) has also voiced a trainer who abandoned a Fire-type starter before.
- Celebrity Voice Actor:
- Series regular Shoko Nakagawa voices Nurse Joy this time around.
- Sorrel is voiced by veteran actor Kanata Hongo.
- Model Shiori Sato provides the voice of Verity.
- Bonji is voiced by theater and film actor Arata Furuta, and in the English dub, he's voiced by Mike Pollock.
- Edited for Syndication: Disney XD's showing of the movie entirely cuts any expository scenes that happen after the movie ends, replacing it all with a quick credits list.
- A fan-theory that arose about the film is that it's a prequel to the Sun & Moon anime, which was described by an art director as "not a continuation of XY." Misty and Brock making a guest appearance in Sun & Moon, complete with flashbacks showing Ash wearing his original hat, more or less shoots this theory down.
- That Verity's mother is Cynthia, which the director debunked when he was asked about it by Shoko Nakagawa. Although... by the way he goes about it, it seems he was rather coy about addressing it. He does acknowledge that they do resemble each other, but you can tell that they are separate because of their different hair colors and he goes on to say that "Verity's mother is her mother."
- Milestone Celebration: The 20th Pokémon movie, and one that hearkens back to the first episode as it's also celebrating the anime's 20th anniversary.
- Pop Culture Urban Legends: For a while, rumors floated around that the movie contained a stinger that featured Giovanni and Mewtwo, the latter clad in its armor suit from Pokémon: The First Movie. These rumors were later known to be false.
- Role Reprise: In the German dub, Pikachu is voiced by Sabine Bohlmann, who last voiced the character over 15 years ago.
- In the English dub, Michele Knotz reprises her role as Nurse Joy for the first time since the penultimate episode of the Diamond and Pearl series.
- The original Japanese version features Kyoko Hikami as Erika, reprising her role from almost 20 years earlier.
- Screwed by the Lawyers: While the English theatrical release of the movie includes a bonus music video celebrating most of the movies, Pokémon 4Ever, Pokémon Heroes, Pokémon: Jirachi: Wish Maker, and Pokémon: Destiny Deoxys are markedly absent, as the retrospective skips from the third movie to the eighth movie twice. This is likely due to remaining contracts with the original English distributor of those films, Miramax Films.
- What Could Have Been: The director of the movie had a few minor ideas for what this movie could have been, including a straightforward Sun and Moon-era movie and even an "All-Stars" movie, reuniting many of the past heroes and heroines with the current cast. Ultimately, they chose to go with the retelling due to the fact that, as a Long Runner, not many new fans know how Ash and Pikachu first met.
- Word of God: It's been confirmed that Verity is NOT the daughter of Cynthia, the Sinnoh Champion, contrary to popular belief at the time.
- Word of Saint Paul: Kunihiko Yayuma revealed some during an interview, including:
- This movie being a What If? scenario had Ash found the Rainbow Wing dropped from Ho-oh.
- This version of Ash being more fashionable and his redesign influenced from Ken Sugimori.
- The number of Spearow chasing Ash and Pikachu increases 20 fold, totaling 1,000!
- Shoko Nakagawa representing 20 years of the Pokémon franchise as she started from playing the original Red/Green versions, resulting in her playing as Nurse Joy, an older sister figure.
- Ash being forever 10 years old.
- The two Trainers in the opening are indeed Neesha and Corey from Pokémon: The First Movie.
- Unlike the original god, he states that Verity isn't the daughter of Cynthia—her mother only resembles her.
Trivia / Pokémon: I Choose You!