If I had to guess, based on the little info we have and the (possible) blood in that video, I'd say that he flew out of the raft on that bump and then the raft kept going and he landed on the slide. So basically the mesh kept him from flying off the slide completely but it did little else for him if he was ejected from the raft.
All speculation, of course.
I am truly horrified by the whole thing. People assume rides are mostly safe in parks. And with no age restriction, I'm sure these parents thought the same. It's so sad. IF the ride ever reopens, I bet the age requirement will be 16 or maybe even 18.
There are other pics on the web with different views of what appears to be blood in the water at the end of the slide, but I won't link them. It's just so heartbreaking and gruesome to even think about. Hard to "unsee" that.
If Caleb was airborne or partially ejected when the injury happened, which it seems almost certain he was, the other women's head and face injuries described in the article above were also very likely caused by the collision/ dragging against his entangled little body. Especially if he was the front rider, which is what a number of comments elsewhere have said he was seated.
There are also some witness comments that say the front velcro restraints weren't working properly earlier in the day, but that hasn't been confirmed by the park spokesperson.
Sounds to me like a combination of a borderline unsafe ride by it's angle, forces, and design (that was "altered and patched up into service" so it could open in 2014). that was even
less safe for smaller and lighter riders, possibly combined with airborne head/ neck entanglement, due to ill fitted, or malfunctioning restraints.
Some comments elsewhere have questioned if the little boy was trying to stand up. I highly doubt this would even be possible, given the speed, angles, and forces at that part of the ride. The presumed area of entanglement is on a part of the slide where powerful water jets assist the forward momentum to push (and accelerate) the raft up and over the second hill, as I understand it.
Some comments elsewhere say he was ejected and "run over" or hit by another raft, but IMO, that's impossible for a number of reasons.
If he was ejected, or more likely, snagged out of the raft, and made contact with the other riders and the slide after the raft continued, the water jets could have pushed his body to the end of the slide, where the large pool of (presumed) blood is. (Hard to think about this.)
IMO, this ride will never be re-opened. I agree with others who think it will have to be taken out of service and dismantled.