Emilia Pérez, despite the fact that she's supposed to be a Mexican cartel leader, speaks with a Spaniard accent rather than a Mexican one, pre-transition and post. In fact, none of the Mexican characters in the film actually speak with a Mexican accent nor do they share identical accents. In real life, despite numerous South American countries speaking the same Spanish language, they still have different accents and lexicons for their own spoken Spanish. A Cuban speaker for example will not sound similar to a Puerto Rican speaker.
Despite the fact that Jessi is supposed to be a native Mexican, not only does she not speak with a proper Mexican accent, but almost none of her spoken Spanish is grammatically correct (and at some points, Selena Gomez as Jessi is even speaking gibberish).
When Rita is researching options for sex change operations there is a screen on the laptop with the caption Cosmetic and Plastic Surgery, 4 soi Sukhumvit 11, Wathana, Bangkok. This is an address in the nightlife area. There is a coffee shop but certainly no clinic for this kind of treatment.
When Emilia meets Rita for the first time four years after her gender-reassignment surgery, she pretends she doesn't know Rita and they start speaking in English. Rita speaks with an American accent and Emilia asks her: "are you English?", and Rita says she's Mexican. Nobody would mistake an obvious American accent like that for an English/British accent.
Emilia has a full beard despite saying that she's been taking hormones for two years and has developed breasts. Trans women don't grow beards like that while they're on hormones.
A French title card misspells the Indian city as "Dehli".