Continuity mistake: Billy and Wyatt and the two commune women are having a swim in a water basin. Wyatt is sitting on the rim, splashing his feet in the water, and 'his' girl starts swimming towards him. Then it cuts to a frontal close-up of her smiling at him, but you can still see his feet splashing in the background.
Trivia: When Wyatt, Billy and George Hanson enter the diner, all the people in the diner were local inhabitants of that town - none of them were actors. Same for the two rednecks who shoot Wyatt and Billy from their truck, at the end of the film - they weren't actors and that was their pickup truck.