Failed is one syllable with a diphthong (a "two-sound") resulting as a glide from the 'a' to the 'i' and one smooth pronunciation.
Vial is ordinarily considered to be two syllables, but in some English accents it becomes one syllable through a process called monopthongization, where a smooth glide between two vowel sounds becomes one vowel sound. As read, vial ought to be read viy-al, but most English speakers pronounce this sound as a monopthong (a "one-sound") and it becomes "vile".