Couple of tangential thoughts:
(1) It's hard to say what would stand out. If you wrote a story set in America where someone ordered drinks and food at the same time, as an American, I can't say that it would give me a moment's pause. Rare? Sure. Unheard of? No.
On the other hand, I'm reminded of a movie I once saw that was made in Britain and set in Britain, in which there is a character who is supposed to be an American who at one point says, "I have to make a trunk call to my solicitor." I found that very jarring: an American would say, "I have to make a long distance call to my lawyer." But I was amused to see that in fact it was deliberate: at the end the clever detective points this out and reveals that the person is an imposter. (The catch for me as a viewer was that I assumed it was the writer's mistake and not the character's.)
There are some things that will leap out of the page, and others ... won't.
(2) As you learn about such cultural quirks, be careful not to overdo them. I recall reading a story once written by an American and set in Britain that struck me as one long string of cultural references. In one short story he brought in Britain's television tax, Middle-Eastern immigrants, Jaguar, royalty, many many words that are different between the dialects of English, and on and on. I got the impression that the writer was either trying to impress us with how much he knew about English culture or was just fascinated by the differences. But it really detracted from the story. It's one thing to get it right when it comes up, it's quite another to go out of your way to bring up every regionalism you can think of. To a certain extent, it adds color, but beyond that, it's just distracting.
(3) Bear in mind that this is not just an issue between countries, but between sub-cultures within a country. Like, I'm a Fundamentalist Christian, and I often get a laugh at how "my folks" are portrayed in fiction. Not just when someone's obviously trying to paint a group he doesn't like in a bad light, you expect that, but even mundane stuff. For example, I once saw a movie where a Christian character is going on a trip and as he's about to leave another Christian character says, "The Lord be with you." And he replies, "Yes, and may God bless you while I'm away." And they go back and forth through a half dozen "God be with you" kind of statements to each other. Any one of them would have sounded plausible to me, but no, we don't go back and forth with the bless-you's like that. We just don't. It's like the writer took every religious-sounding statement he had ever heard and strung them all together.
I live just a few miles from Detroit. But if I tried to write a story set in a black neighborhood there, I wonder if someone who was actually from that neighborhood would find it absurdly unrealistic. Ditto if I tried to write about wealthy investment bankers. Hey, I remember when I was in high school I was one of the science-club geeks. At one point I dated a girl who was in orchestra and the arts crowd, and I was struck by how different our sub-cultures were. I went to parties with her friends and the topics of conversation were just so different, etc.
Frankly, I think this is one of the biggest challenges facing any writer who tries to write about people who are not from his own little group. Ooh, reminds me of a book review I read once. A politician named Spiro Agnew had written a novel. I never read the book, but I read a review where the reviewer said that many people were interested to see if characters in the book would be thinly-veiled representations of real people. And then she wrote, "They are. They are all Agnew." She went on to say that ever character in the book thought and acted just like Mr Agnew.