Corrected entry: At the time the picture was made, there were helmet laws in every state they passed through except California. It seems established that a helmet is the one thing Jack Nicholson needs to join them on the trip. In an environment in which the law was champing at the bit for an excuse to bust them, it seems odd that Dennis Hopper manages to ride his bike from Arizona to Florida without a helmet.
Corrected entry: In the scene at the hippy camp, where Wyatt and Billy are sitting against a large rock, just before accompanying the girls to the swimming hole, Billy passes a joint to Wyatt who takes a drag on it, gathers up his stuff, and walks away with the joint in his mouth. As Wyatt departs with the joint between his lips, it appears between the fingers of Billy's right hand. Billy glances at it, then stubs it out on the ground as he gets up and departs.
Corrected entry: At the beginning of their ride Wyatt and Billy come to a farm where two men shoe a horse. One guy holds the obviously cold horseshoe with his hand, hammers on it, and then nails it to the hoof. If he'd just refit it because the horse had just lost it he wouldn't hammer on it, and if it were a new one he would have to heat it till it's red hot. (00:13:10)