The trees were fake
Dirty Dancing was set in the Catskills in the height of summer, but the film was actually shot in fall, which proved to be a problem for the color of the leaves on the trees. All of the leaves that were in the camera shot had to be spray painted green to be in line with the rest of the movie.
With many of the cast wearing loose, summer appropriate clothing, they were actually freezing and had to bundle up in sweaters and big coats in between takes to keep them warm in the outside sets. It’s a good thing they had to dance the whole time, at least they could warm up in some way.