Factual error: The movie takes place in New York City, yet a sign on the ice cream store where the mother works says "Take Away." I know they call it "take away" in Britain and Ireland, but in New York it is called "take out." The movie was filmed in New York and Ireland, so that shot was probably filmed in Ireland.
Factual error: When Christy performs a song on the school stage Johnny videotapes her from the audience. In the monitor we see a close-up of a part of Christy's face which would require a tele zoom with a factor many times of what a camcorder would feature even today (the movie is set in the early eighties), plus it's also too steady for a hand-held camera.