There are different accents among different areas within a given country. If you're from one city or region you may have a different accent than someone from another city or region. It's noteworthy that Cubans that arrived in the U.S. after Mariel (1980 onwards) not only speak Spanish different than the Cubans from the original migration wave (circa 1960-1966), but some also even look a different "type." So many people left that unfortunate country that even the traditional ethnic mix was altered and the culture itself was affected accordingly. Pacino's take on the "Cuban" accent is just as valid as Robert Duvall's Cuban accent in "Wrestling with Ernest Hemingway," which, by the way, is another fine performance.