One of the main issues that causes controvesy is the amount of shots fired and the time between the shots. The main conclusion was there was only 3 shots: the one that hit both JFK & Connelly, the head-shot & the one that missed and caused injury to a bystander near the underpass.
The spacing between the shots is based on dictabelt recording, which came from one of the police cycle riders who had left his mike on. Sound experts analysed the recording and identified noises which could constitute gunshots. These experts then tried to replicate the sound pattern by experimenting with mikes all along the route & estimating where the police cycle was . Their conclusion was that 4 shots were fired and one had to be from the grassy knoll.
But there are a couple of issues with this.
1. It wasn't 100% certain which officer had left the mike on (They based it on being McClanes being the most likely).
2. Other/later footage shows that its likely they then estimated McClanes position wrongly by some distance.
This fueled a lot of the Conspiracy theories.
Also, many assume the order of the shots was as follows:- 1. JFK/Connelly shot 2. Headshot 3. The 'Miss' that injured the bystander near the underpass.
But there is plausible theory that 'missed' shot was actually the first one taken, and was deflected off an overhead gantry towards the underpass.
Once you marry up that sequence with the sound recording you actually end with about an 11-12 secs spacing between the first & last shot.
So 3 shots in 11secs compared to 3 shots in 5-6 secs would be reasonable for an average/good marksman.