Deliberate mistake: The same group of people wearing the same clothes, including a dancer and bartender, are shown sitting around a bar on two different disco nights. On the first disco night we see them when Tony leaves the bar to go outside after being informed by Joey, what Double J is doing in the car. We see these people again at the start of the second disco night, both nights when we see them, the song "If I Can't Have You" is being played. (00:21:20 - 00:56:30)
Saturday Night Fever (1977)
1 deliberate mistake
Directed by: John Badham
Starring: John Travolta, Barry Miller, Joseph Cali, Karen Lynn Gorney
Continuity mistake: When Tony walks into 2001 that first night, he shakes hands with some guy as he is walking through the club and again a few minutes later. (00:13:00)
Connie: Are you as good in bed as you are on the dance floor?
Trivia: When Tony Manero's father slaps him on the back of the head during an argument at the dinner table, Tony replies, "Would you just watch the hair? You know, I work on my hair a long time and you hit it! He hits my hair!" John Travolta ad-libbed this line. Director John Badham thought it was so perfect for the character of Tony Manero that he decided to leave it in the film.