In the scenes involving driving the horse to the horse whisper, half of the time the horse box is missing from the back of the car, and in some scenes magically re-appears again.
Okay, I don't know what scene you're talking about. No offense, but I am a horse back rider. I do it for a living. Their called TRAILERS. Anyway, I think that the scene you are talking about is... when they drop the trailer off at the motel and then they go to look for the whisperer. I think.
I'm a rider too, and I agree with the above statement. I don't remember a time where it showed the truck not pulling the trailor when it was suppossed to. I believe that they stopped a few times and unattached the trailor from the truck.