I'm pretty sure that whether the word is written on the poster or not it must be pretty obvious to even the most stupid of non-Americans that Captain America is in fact American - and a captain there of - I don't think when released abroad all of the "Captain America" lines will be dubbed to "Captain {COUGH}" so although the director may have said something stupid - though i'm taking it on faith from a tertiary source that this is what's said here - the poster is a great design and the character is SO well known the world over that Captain America is written on the poster in bolder letters than letters themselves could ever convey by the character and uniform themselves.