In the diner, George Hanson enters wearing his football helmet. When he begins to sit down, his reflection in the mirror shows him rubbing his eyes. The next shot shows him just sitting and the helmet is already on the table.
After Wyatt asks the farmer permission to repair the motorcycle tire in the barn, the cowboy who is shoeing a horse puts his left arm on the horse's back. Between shots he appears with his both arms by his sides.
When Wyatt throws away his watch at the beginning of the film, a close-up shows that it is 20 minutes to noon, but as they pull out onto the road the lowered sun reveals that it is more like 3:00 or 4:00pm in the afternoon.
In the first camping scene, Wyatt and Billy sit by the fire in high grass and thick foliage, next to an abandoned vehicle. When they wake up in the morning they're in a barren southwestern landscape, with no vehicle in sight.
Wyatt and Billy are going to the Mardi Gras celebrations in New Orleans. This indicates that they are traveling in either late January or early February, given that Mardi Gras usually takes place in mid February. Despite this, and despite the number of states they drive through, the men never drive through an area of cold weather. Many of the characters they meet are wearing summer style clothes, and the weather is most obvious in New Mexico, where the winters can be extremely hard with lots of snow.
Flipped shot: in the first shot of Wyatt with the motorcycle, the "Captain America" jacket is seen in reverse - the vertical strip and badge is on the left side of the chest and in the last second when he departs, the flag is reversed too.
The scene just before Wyatt throws away his watch is a mirror image. The bike appears to be leaning to the right on the kickstand (instead of the left) and his jacket has stripes down the right side but in the rest of the movie they're down the left side.