I just found out that there was an another movies about the Kennedy assasination. It's called Executive Action and instead of following Jim Garrison it follows a bunch moneybags and the guys who supposedly killed him. It predates the Stone movie.
Nothing would suprise me about the Kennedy Assasination but i dont know enought to adopt any of the conspiracy theories regarding. It's a good movies but you need a strong stomach to watch it. Not because of the violence.