The correct spelling of the phrase "red favourite" is a matter of debate, as it can be spelled with either American or British-English spelling conventions. In American-English, "red favorite" is spelled with the short "a" vowel sound, as in [rɛd ˈfeɪvɹət]. In British-English, "red favourite" is spelled with the "ai" diphthong, as in [rɛd ˈfeivərɪt]. It's important to note the differences in spelling to avoid confusion and ensure clear communication in written and spoken English.