Agree with other comments although you could crop slightly less tight i.e. to top of light reflections as suggested by Des. Not sure why you have cropped a little from the RHS. You could use the perspective crop or skew tool as suggested by David A. to straighten the LHS which will also remove the slope on the letters on that side.
As an irregular attendee at horseracing, I am aware that we look odd photographing the crowds when the racing is behind us, but that is where the pictures are. A pleasing image of human response particularly as a letterbox.