Human Nature

Lila Jute

Puff

Dr. Nathan Bronfman

Police Detective

Police Detective

Police Detective

Young Lila Jute

Doctor (as Stanley Desantis)

Frank

Puff's Father

Congressman

Congressman

Young Puff

Young Nathan

Nathan's Mother

Nathan's Father

Louise

Wendall the Therapist

Gabrielle

Wayne Bronfman

Bistro Waitress

Aversion Therapy Model (as Laura Grady Peterson)

Chester's Waitress

Stripper

Lecture Host

Puff's Mother

Reporter (uncredited)

Steven Soderbergh was first interested in directing Charlie Kaufman's script back in late 1996, when Kaufman was still trying to get Being John Malkovich (1999) produced. Soderbergh's considerations for casting were for David Hyde Pierce in the role of Nathan Bronfman, Chris Kattan in the role of Puff (likely due to his character Mr. Peepers on Saturday Night Live at the time), and Marisa Tomei in the role of Lila Jute. He was about to go into pre-production when he was offered Out of Sight (1998) and after much deliberation he left the project.

The studio originally wanted Spike Jonze to direct the film because of the success of Being John Malkovich (1999). He considered it, but opted to produce, and suggested Michel Gondry, instead.

Many of the scenes in the forest are allusions to or recreations of scenes in the Björk music video "Human Behavior", also directed by Michel Gondry.

When Dr. Bronfman (Tim Robbins) enters the woods with the pistol (a German Luger) there is the sound of the hammer of a revolver being cocked - but a Luger does not make a sound like that.

Puff: Words are evil. Are they not evil, these words we use? Hmm? Does anyone know the definition of simultagnosia? I meant to look it up before Lila saved me.

Nathan Bronfman: Remember, when in doubt, don't ever do what you really want to do.

Puff: Apes don't assasinate their presidents, gentlemen!