I remember watching Batman Begins, and Christian Bale dropped an awful line in Mandarin but pronounced some words like Cantonese (he butchered "I'm not a criminal" into "I'm not a rice wheel / cloud"). I'm always amazed that how much are the actors getting paid, yet can't afford to hire a language coach or just some random person from Chinatown to be on set and help them rehearse just one line of sentence that has 5 words in it (我不是犯人)

I'm reminded of this because, I was watching season 2 of Fringe yesterday, in one episode, Peter Bishop (Joshua Jackson) claimed that he could speak some Cantonese, and he indeed spoke a couple of okay Cantonese lines in that episode, he didn't sound like native, but it's believable enough as a character who needed to learn the language to do some shady dealings in the past. The lines were not butchered or sounded exaggerated, and I don't think Joshua Jackson himself was getting paid in millions while filming Fringe.

It's even more jarring when Hollywood hires Asian actors to do lines in Asian languages that are not their native languages. I've heard this quite often, when they hire a Korean actors to speak Mandarin / Cantonese, and they sounded awful.

Also, in Japanese shows, I have no idea why they kept making the actors who can't speak English, speak English. In Shin Godzilla, Satomi Ishihara's character is supposed to be a special envoy for US President (IIRC the character grew up in the US), and her deliveries totally broke the immersion. The funny thing is that the other Japanese native characters who didn't grew up in the US, delivered more convincing English lines than hers. Japanese directors, you don't need to speak English to look cool, it's okay for the characters to speak Japanese in Japan.

Hire a language coach, they have already been hiring dialect coaches for decades, why not hire a language coach for a few days? (of course not, the money needs to get into Zaslav's pocket)