According to my dictionary, the word vial should be pronounced /vaiəl/. But I've heard the pronunciation /faiəl/. Is that a mistake or merely a dialect?
Expanding on my comment, there are in fact two words in English -- vial and phial. The meanings are identical, though as a native speaker I will admit that they "feel" a little different. Namely, phial feels a little old-fashioned; maybe because the ph makes it look closer to Greek. It feels right to me that modern scientists put their liquids in vials; but alchemists of the Middle Ages definitely would have used phials.
Google ngrams seems to support this feeling of old-fashioned-ness. American English has fairly consistently preferred vial. British English preferred phial until about 1840, but since 1960 or so vial has taken hold. English fiction also preferred phial until about 1970 -- perhaps because it adds "atmosphere" to the story.
Etymologically, the words are, as one might imagine, closely related -- both came from Old French fiole. But phial isn't actually older -- the two variants are about equally old, both appearing in the late 14th century.