- Bad Export for You:
- When the triple-film DVD came out in 2009, many expected all three movies, including this one, to be widescreen unlike the previous VHS and DVD release. Sadly...no dice. This was later remedied with the triple feature Blu-ray release in 2016, though the releases add problems of their own, as detailed in the note in the Keep Circulating the Tapes entry below.
- No Western DVD release has included the Japanese version. This is par for the course for Pokémon, but the Japanese version of this movie is in greater demand than the other movies due to its differences from the English version.
- Cowboy BeBop at His Computer:
- Mew was, at least for a short period, mistakenly referred to as Mewtwo's mother rather than its clone counterpart. This also ignores the franchise's (mostly) strict adherence to gendering Pokémon.
- According to TV Guide and the Comcast information guides, the plot of the film has Ash and friends battling Mewtwo and the scientist that created it — despite the fact that Mewtwo killed said scientist within the first few minutes of the film.
- The Danza: Raymond, the pirate trainer Ash faces at the beginning of the movie, is voiced by Raymond Johnson.
- Keep Circulating the Tapes:
- This film as well as the latter two movies took years to get a Blu-ray disc release thanks to years of disputes between Warner Bros. (the licensees of the movies for all territories except Japan), The Pokémon Company, Nintendo and Toho. By The New '10s, fans were getting irritated over having to deal with the 4:3 aspect ratio of the DVD and VHS releases and pushed for the disputes to end so they could get the films remastered for high definition. The disputes were finally resolved in December 2015, and a Blu-ray disc release of all three movies in a triple-feature Steelbook pack was announced for release in February 2016, in time for the Pokémon franchise's twentieth anniversary!note
- The 1998 theatrical version of the film has remained under this status since the release of the kanzenban version a year later. The latter version re-does a large number of shots in the film to add in CGI (be it replacing entire effects such as whirling clouds or simple choreographic retouches); this is the version that would be used for the film's English dub and all following home video releases. The theatrical version, meanwhile, has never seen a single re-release since its initial VHS & LaserDisc pressings in the first half of 1999, and only continues to survive thanks to the likes of eBay, Amazon, and a small number of video-sharing sites in the most obscure corners of the internet.
- Weirdly enough, the "Mewtwo's Origins" short, which is also the actual first 10-minute opening of the film, has yet to be released overseas past its initial DVD release. It was dubbed into English, and they have every audio master to everything Pokémon that 4Kids dubbed, so re-inserting the segment with its dub wouldn't be that hard. It also makes some things in the film more clearer, like Mewtwo's characterization, why its Charizard, Venusaur, and Blastoise have weird markings on them, and why it came into creation in the first place. The film flows better with it, so not at least including it as at least a bonus feature for the later releases is baffling.
- Pop Culture Urban Legends:
- It's been revealed that the reports of the death of Mewtwo's original VA have been greatly exaggerated. And he apparently voiced Mr. Fuji as well, instead of Maddie Blaustein.
- It is commonly believed that the movie was originally meant to be the finale of the series before the anime was renewed, due to the Japanese teaser trailer having scenes that aren't in the movie. However, the anime was renewed before the film even entered pre-production, and it was never actually intended as anything more than a side story.
- It's commonly stated that in the Japanese version Mew has a line about how the clones are "inferior and should die". This is either a mistranslation or an outright lie. The actual line is roughly "The real ones are real. If the clones fight only using their bodies and not with skill, the real ones will never lose."
- Throw It In!: The commentary remarked that Misty's "please, no" reaction to Ash's "death" was originally, jokingly ad-libbed by Rachael Lillis as "My bike!" when trying to find a workable two-syllable reaction to said event.
- Unintentional Period Piece: The English dub's soundtrack is a nice little time capsule of late 90s bubblegum pop.
- Vanilla Edition: The current Region 1 DVD - it only has the theatrical film it lacks both the 10 minute prologue that was on the original VHS and DVD and even the accompanying Pichachu short that was shown before it in theatres.
- What Could Have Been:
- The Japanese teaser trailer consists entirely of scenes from an earlier draft of the movie.
- One of Takeshi Shudo's blogs revealed that there would have been an anime episode prior to the movie where Ash and Mewtwo crossed paths, but the four-month hiatus brought on by the "Electric Soldier Porygon" incident put an end to that.
- Mew could originally speak like Mewtwo could, but director Kunihiko Yuyama figured Mew flying around wordlessly would be more impactful than it "droning to Mewtwo about the meaning of life", thus all its dialogue was replaced with, "Mew".
- The scene of Ash saving Pikachu from the cloning machine wasn't originally present, but was added by Yuyama, who believed the film didn't have enough action scenes.
- According to Rachael Lillis, Warner Bros briefly considered replacing the entire voice cast with celebs, and even made an offer to Leonardo DiCaprio to voice Ash.
Trivia / Pokémon: The First Movie