Yeah i think more that Oswald was involved, therefore a conspiracy. I don't buy into the Oliver Stone conspiracy though.
Oswald shot Kennedy and Connolly and there is no evidence that he conspired with anyone. But the head shot that killed Kennedy may have been an accidental round fired by the Secret Service. A book has been written with this scenario--Mortal Error. The ballistics check out and it's the only good explanation for the clear insider cover up and disappearance of evidence that happened after the shooting. The only conspiracy theories that make sense to me are the Texas Oil Billionaires (HL Hunt, Clint Murchison, Sid Richardson) putting Lyndon Johnson in office or The Mafia going after The Kennedys in retaliation for Bobby Kennedy's war on organized crime. But neither of these account for the massive insider coverup.
I don't believe it's a conspiracy, because the of the number of people required to pull off such a huge event, there is no way all of them would have kept quiet for such a long time. Just look at Bill Clinton and Monica Lewinsky, just the two of them were involved, and they couldn't keep it quiet.
stone has gone on record before saying his movie should not be thought of as a documentary. he took bits and pieces of several different theories, and sewed them together into an entertaining movie.
the "magic" bullet. some sniper dude duplicated that shot on the discovery channel (might have been history channel). dude was able to inflict nearly identical wounds, and be left with a bullet in similar condition to the "pristine" on found at Parkland hospital.