Yeah, a lot of them. There are many different conspiracy theories...most of which have little or no concrete evidence, most of it is speculation. One theory is that it was LBJ's work, Kennedy being his gateway to power. Stone asserts this theory in his movie by citing an executive order or something that Kennedy issued, it basically said that the U.S. would not go to war with Vietname while he was in power. Other theories say it was the U.S. Army, CIA, joint effort etc etc. Garrison, Stone's hero in his movie, tried to implicate a man, Clay Bertrand alias Clay Shaw, in court. But it is hard to sa there is a concrete connection, Garrison seemingly has evidence that Bertrand was a CIA agent, and he had previously had a homosexual relationship with a man (played by Joe Pesci in the movie) who had met Lee Harvey Oswald a few times. The connection is loose and probably is not even true. Even so, the movie is interesting, but still a movie. The real documenteries I have seen have some more credible experts, so to speak, putting forth their theories. As I'm sure you've heard before, the grassy knoll is the most peculiar aspect of the assasination. I have seen both in the movie and the documentaries that there were eyewitnesses that saw and/or heard shots being fired from the grassy knoll that was to the front and right of Kennedy's position when the fatal shot struck. This is where the movie claims to be most credible, as it shows repeatedly the actual film of the fatal shot hitting Kennedy, it is very gruesome. Believers of the grassy knoll theory say that because Kennedy's head goes back and to the left when the fatal bullet hits, the bullet must have come from the front right...which would be the grassy knoll. The speculation starts with who was on the grassy knoll and why...then the theory loses more and more credibility. The best program I have seen regarding the assasination, which concludes that Oswald was the lone shooter and acted alone, thus no conspiracy, says that because Kennedy's head goes to the back and the left does not mean the bullet had to come from the front and right. This is supported in the program by gun experts and military people. In that same program, a computer expert, pretty brilliantly, recreates the entire scenario on computer by using the actual film. The man who took the film was a civilian...I'm not even going to attempt to spell his name and I'm too lazy to look it up, but if you've ever seen the grainy color picture of Kennedy's limo rolling down the street, that's the film. Anyway, the guy who made this on the computer also recreates the bullet paths of each round Oswald got off with great accuracy and he backs them up with movements by Kennedy and the Governor of Texas, forget his name too. The first bullet flew overhead, and you see in the film both Kennedy and the Governor turn their head as the bullet flies over their car. The second bullet was a hit, this is the famous hit they always show but interestingly enough it was not the fatal shot. Stone calls this bullet the magic bullet, because of it's interesting enter and exit pattern, but the computer recreation destorys this theory as well. Stone claims that Kennedy was sitting to the left of the Governor (Kennedy in the back seat, Governor in front), so when the bullet entered the back of Kennedy's neck and out the front of his neck, the bullet magically made right turn and entered the Governor's shoulder, exited, and hit him in the right thigh. However, Stone is completely wrong. Kennedy's seat, by the make of the car which Stone somehow overlooked, was right behind the Governor, so the bullet hit Kennedy in the neck, came out the front, pierced the seat and the Governor's shoulder and then hit him in the leg. The film supports this, erily again, right after Kennedy grabs his neck, the Governor slouches to the right. The final shot was a direct hit to the back left of Kennedy's head, simple enough. All of this physical evidence in line with what I talked about in my previous post is the most concrete theory on what happened. Like I said, there are a variety of different theories, some based on some small element of truth, but most are purely speculation.
If I missed something or got something wrong which is highly unlikely
....I apologize, I was too lazy to check it after writing such a long post.