My reply as an Italian nerd:
USA's pop culture is quite popular, especially for those interested with your media in the first place. I noticed that most of the fiction translated in my language, though sometimes adapt away pieces of American pop culture etc. that could be more hardly understood by the wide audience.
Personally, I don't have real trouble catching many — if not most of the pop-culture references, and have slight more trouble withthe hystorical ones; but Wikipedia is on click away, so in a way there's less problem with references in the written media, which are easily researchable, than ones in a movie/TV series ("oh, shit: and now, how do they spell THAT name? How do I look up for it?!").
Conversely, I sometimes have HUGE problems interpreting some of the more meial stuff, like stuff that for an american citizen is day-to-day, menial details, but for me are totally alien. As I already stated before, I have problems wrapping my head around how an actual high school works, and despite it being quite often portraid in fiction, me writing about it in a fanfic is a really tricky subject — and one I'm really hard pressed dancing around. So if you or other american authors write of details in that category, I take them as bona-fide, 100% factual reality: over the course of a school day, a high school student can exit the school to go buy a V-day present to a girl? Good to know: in Italy, instead, minors going away during school hours without notifying (and justifying) the exit is prohibited, for what I remember about the subject.
…And so on.