Diane Lane wanted Viggo Mortensen to be in the film so much that she gave up part of her salary so that the production could afford him.
Diane Lane commented in an interview, "If Viggo and I convince people we're enjoying every second of that encounter [in the waterfall] we've really done our job as actors. It was freezing in that river. The water was filled with debris and cigarette butts and the rocks were covered in little worms."
Dr. Fogler's Bungalows was based on a real Catskills bungalow colony called Dr. Locker's which existed for many years in the sleepy Sullivan County hamlet of Mountaindale, NY. It was where writer Pamela Gray spent her childhood summers.
Much of the licensed music in the movie is by acts who performed at Woodstock, but two famous names associated with it actually were not there. Joni Mitchell felt she had to decline her invitation, but later composed a song ("Woodstock") about the festival. Big Brother and the Holding Company were never invited. Janis Joplin had left them the year before, and she performed there with the Kozmic Blues Band.
Tovah Feldshuh was only 46 when the film was made, and in real life is not quite 15 years older than Liev Schreiber, who plays her son in the film.