John Travolta, who played Danny Zuko in the movie, was at this time already a major star, a well-known celebrity, especially after starring in the movie Saturday Night Fever the previous year, in 1977.
"Night Fever" is a disco song, written and performed by the Bee Gees. It first appeared on the soundtrack to Saturday Night Fever. Producer Robert Stigwood wanted to call the film Saturday Night, but singer Robin Gibb expressed hesitation at the title. Stigwood liked the title Night Fever but was wary of marketing a movie with that name.