Jonathan Kelly's hair length changes many times throughout the entire movie.
The first time David follows Jonathan home, Jonathan is wearing a different shirt when they arrive at the house than he had on when they were walking through the field. This was due to the two scenes being filmed weeks apart, and the shirt being misplaced in the meantime. An attempt was made to film the scene so that Jonathan's chest always remained turned away from the camera, and the result was somewhat awkward.