After the big race, Johnny's car is shown pulled into a parking space front first. But, when he goes to drive off, from an overhead shot, his car is now in a space where it was backed in.
When Johnny marks the note on the horse "paid in full" at the track, he is writing in a small area of the paper with a ballpoint pen. Later, when Ann hands Joel the paper, the writing is across most of the document and a marker or grease pencil was used as the lines are much thicker than a ballpoint could make.
When Joel fights with the man sent to fire him, he pushes the guy through a wooden railing and it can be seen where the board has been pre-cut. In subsequent shots, the ends of the board are more splintered. Also, one end of the board appears to be attached to the post by a hinge.
At about the 06:30 mark the shadow of boom mic moves across the left post of the clockers' stand, above where Ralph Meeker is standing.