It was the argument in the Everglades that made Susan understand Kane for what he really was, and it was the argument that made Susan understand what she had to do to save herself.
The picnic scene itself was interesting in different ways. First, there was the sequence leading up to it, a brief exchange between Kane and Susan at Xanadu, Kane's personal palace, during which Kane informed his young wife that they would be having a picnic whether she was in favor of it or not. Composed of a mixture of medium shots and deep focus, much of Kane's figure was obscured by shadow, and he could only be completely seen when passing Susan's place at her puzzle. During the actual meat of the dialogue, Kane was almost completely engulfed in shadow. This was interesting because during the exchange in the tent, Kane was almost completely illuminated, and while there were harsh shadows, they fell in places that would have been natural for the placement of the lantern within the tent. The juxtaposition here was really amazing. At Xanadu, Kane was asserting himself to great effect while completely obscured by shadow. In the Everglades, Kane's assertions and violence were ignored by Susan because she saw him in the light, she saw what he really was. .
The angles within the tent were also worth mention. For most of the film, Kane was shot at low angles, giving him the illusion of power, and in this scene low angles were used as well, but not in as many shots as would be expected. The scene itself was almost wholly comprised of an argument between Kane and Susan. She insisted that he had never given her anything she really wanted, which was a recurring theme in all of her speeches as her relationship with Kane progressed. She became shrill and almost hysterical, but she maintained unwaveringly that Kane couldn't care about her, because he didn't give her anything that was important to him. And then she came to a realization that changed the course of the entire scene.
