The scenes of the dead duck and the snake were real incidents from writer/director Viggo Mortensen's youth. He told the stories over a couple of visits to Late Show with David Letterman (1993).
The film was made on a very limited budget, and Viggo Mortensen not only worked for free, but also used his own money to cover costs: "I hadn't intended to act in Falling, but after failing to finance the film once, and it looking like the second time wasn't going to work either, I thought that being a familiar face as an actor might help investors come on board. I also decided that this actor playing John, namely me, who had some name value, wouldn't need to be paid anything, and that would help give us money for a few more days of shooting. So, as the producer, the director, the screenwriter, and the composer, I didn't need to be paid either. What I did was take the money I was going to be paid and immediately put it back into the movie. Hopefully, the next one I do, I could actually get paid something."
Viggo Mortensen, on working three roles (actor, director, producer) for the film: "Fortunately, Viggo the actor was fairly well behaved. And fortunately Viggo the director was not too unkind or strict with Viggo the actor, so they got along pretty well... Viggo the producer liked the fact that Viggo the actor would be working for free and as a producer, he was also happy that the director was working for free."
Viggo Mortensen cast his son Henry Mortensen in a small role after roping him into a read-through of the script and realizing he could do an authentic upstate New York accent. Henry volunteered to cut off his long hair and grew a mustache to better resemble a state trooper in 1977.