Throughout the film, Johnny and Baby always wear contrasting colors: Baby wears very light colors, and Johnny wears black or something very dark.
The dancing that Patrick Swayze and Jennifer Grey do during the love scene was actually the same dance that they did for the screen tests. It was not originally supposed to be in the film.
In the scene where Johnny and Baby are practicing dancing, and she keeps laughing when he runs his arm down hers, it was not part of the scene; she was actually laughing and his frustration was genuine.
They left it because it was effective. Her falling over in this scene was unplanned too.
The very famous scene where Johnny and Baby are practicing their dancing and they are crawling towards each other on the floor wasn't intended to be part of the film;
they were just messing around and were warming up to do the real scene, but the director liked it so much he kept in the film.
While the exteriors and cabin scenes were filmed at Mountain Lake in Virginia, the lake scene was filmed at Lake Lure in North Carolina in October.
There are no close-ups because the actors were so cold that their lips were blue.
Jennifer Grey, at 27, was 10 years older than the character of Baby. During her audition, she had 5 minutes to prove she could play younger, and that she had the moves for the role.
Lynn Lipton, the actress originally cast as Marjorie Houseman (Baby's mother) was replaced early in the filming with Kelly Bishop, who had originally been cast as Vivian Pressman (the "Bungalow Bunny").
Left without an actress to play Vivian, the producers cast Miranda Garrison, the film's assistant choreographer, in that role.
The book that Robbie tries to lend to Baby as an explanation for his refusal to help Penny is 'The Fountainhead' by Ayn Rand.
Rand was the creator of a philosophy called Objectivism, which holds (among other beliefs) that it is more important for a person to be concerned with his or her own well-being rather than to try to help others.
Some of her adherents (including, apparently, Robbie) interpret her books as justification for selfish and self-serving behavior and the disavowal of responsibility to others.