Trivia

The scene where the falcon starts freaking out was caused by somebody upsetting it from behind. If you look closely, you can see the arm of one of the crew members behind it causing it to be upset. That probably was Dan Haggerty, who is also uncredited for the film, but who worked as the animal handler in it. He later went on to play the title role in The Life and Times of Grizzly Adams (1977).

The winter scenes in which the frozen lake is shown were not shot in the winter. They had to construct a winter scene by sinking cinder blocks into the lake and covering them with plywood, before adding the "snow" topping.

When Sam discovers the peregrine falcon nest, it is occupied by female game birds, not peregrine falcon chicks as is implied. Peregrine falcon chicks are white and downy with a slightly hooked beak. The birds in the nest are most likely female Japanese quails or some similar type of game bird.

Henry David Thoreau was an American author, poet, philosopher, abolitionist, naturalist, tax resister, development critic, surveyor, and historian. A leading transcendentalist, he is best known for his book, Walden, which is about a reflection upon simple living in natural surroundings, and his essay, Resistance to Civil Government (also known as Civil Disobedience), which is about an argument for disobedience to an unjust state.

Henry David Thoreau's books, articles, essays, journals, and poetry total over 20 volumes.

Maxie Rosenbloom: His bit part as a "flint seller" was the final screen appearance for former boxing champion "Slapsie" Maxie Rosenbloom", ending a prolific career of over 35 years as a character actor.