Movies with three or more languages - how can we know?

Over on language hat is a discussion of Robert Worth's nice essay on learning Arabic. In the comments, someone wonders how many Arabics (more than dialects, less than languages - political/cultural considerations feature heavily in the definition) one would need to be able to speak with any Arab one might meet.

Well, that made me remember something that happened last year. I have a friend who speaks Arabic - she studied in Cairo - and we went to see The Syrian Bride together. Afterwards she told me that she was struggling so hard to understand the Syrian spoken by most of the characters that it took half the movie to realize that the photographer was actually speaking Hebrew. I, of course, didn't know it until she told me over dinner after the movie - and it made his character's actions more understandable, and illuminated his relationship with the bride's family, changing the way I thought about it and, in fact, changing the function of his character altogether. I had no way of knowing - couldn't guess, as I did with the Israeli soldiers in the movie, that he wasn't speaking Syrian. For that matter, the UN workers switched between English and French, and one of the bride's brothers had married a Russian woman, and they spoke Russian among their little family - she spoke no Arabic. But everything was flattened out and made equal in the subtitles. All the languages became English. (And you needed to pay attention to realize when people were speaking with each other and when not.)

I've often wished that in multilingual movies the subtitles would make it clear what language each character spoke. When I saw Everything is Illuminated I knew that some of the people he encountered were speaking Ukrainian, not Russian; most of the audience, I'll bet, did not. When I saw After the Wedding I could guess when they were speaking Danish and when they were speaking Hindi, but it wasn't until I looked it up on imdb.com that I saw there was Swedish in it, too. Now I wonder when, why, and who... When I saw The Legacy I could guess that they might be switching to Swedish when the characters traveled to Stockholm, but I couldn't know - I did recognize it when they spoke French, which only made me wonder more if they sometimes spoke Danish and sometimes Swedish. The Danish (and Swedish) audiences would have known.

In some movies it might not matter much. But sometimes it's more than just an interesting fact; as in The Syrian Bride, sometimes who can understand and who cannot is actually important to the story.