Other mistake: In the beginning of the movie, Mewtwo is escaping the laboratory. He blows up his surroundings, then shoots up out of the containment chamber. Later in the movie, Tim and Pikachu see a holographic flashback of that same moment. Although in the hologram, Dr. Laurent is directly in front of the chamber when she wasn't in the beginning of the film.
Other mistake: The Psyduck is technically incapable of defending the group against the Quajutsus. Regardless of which psychic attack Psyduck uses, Quajutsu is immune to it because of its typing (water/dark).
Suggested correction: As an adaptation, the movie is allowed to bend the rules of the game. Furthermore, just because they're strong against psychic-type attacks in the game doesn't mean they'll be completely unaffected or totally immune, especially given how powerful his attack is.
Other mistake: At the beginning, when Tim arrives in Ryme City, a Sneasel is visible with its ears on the wrong sides.
Suggested correction: As an adaptation, the movie is allowed to alter the design of characters and creatures from the games. It doesn't need to stay 100% consistent with the game, and thus, this cannot be considered a mistake. Other Pokémon in the movie similarly have minor cosmetic changes. Furthermore, you could also easily chalk this up to the Pokémon's genetics simply being different. Natural variation or mutations happen sometimes in species, and it's canon in Pokémon that some of them have different forms or look different even if they're the same species. (Ex. I have a number of the same Pokémon that all look completely different in Pokémon Go.)
