At the end when they're on the ferry, someone says "everyone's gone". Who's everyone? What about the parents and other adults? Wouldn't their Mums and Dads wondered where they'd disappeared to? And how come Gavin wasn't with all the other Blue Ribbons?
Perhaps they meant that everyone (parents, teachers) are gone in the sense that they no longer accept their children as the way they are and are lost causes. Or perhaps it's just one of many plot-holes in the film.
I'm banking on the latter.
It's always funny until someone gets hurt and then it's just hilarious!
[spoiler] On the ferry, when Steve caught up with the survivors, Rachel asked him: "What happened?" As in, what happened back at the road block.
Steve answers: "We're the only ones left." The only ones who know the truth about the brainwashing or were brainwashed.
On the other hand, Steve is a 17-year-old teenage boy who just watched over 20 kids die along with an adult friend and had to kill someone in self-defense (Caldicott was telling him "you're dead" through clenched teeth when he was hanging onto Steve's leg), so he was a bit shell-shocked. It sounds like the answer of a traumatized teenager. As an adult now, he'd probably just say "they're gone."
Not to mention still recovering from whatever drugs and the imagery from the aborted brainwashing attempt; the overcame it from adrenaline and the will to survive. Rachel was initially worse-off since she was out of it (and therefore subjected to the process longer than Steve, if only by a few minutes). I wouldn't be surprised if Rachel and Steve suffered from symptoms like cold sweats, fever, nausea, fatigue and light sensitivity for the first few days from the drugs, and nightmares and insomnia and other psychological issues later. That programming was pretty twisted 1950s old value stuff.
That being said, he could easily be wrong. Chug and Lorna may still be alive somewhere, as well as the Bishop Flats 11, and there were two on the ground writhing in agony that didn't join the group. With it being dark and with Steve in a hurry, he could have missed them, forgotten, or assumed they were dead too.
As to everyone else in Cradle Bay, either they fled (the conspirators from the programming center or were observing the experiments), didn't know the truth, or were too scared or blind to do anything.
For instance, after nearly two-dozen kids and two adults died, if you were a corrupt cop who had tampered with evidence, committed kidnapping and accessory to murder among other crimes, would you stick around?
The Alternate ending has Gavin being shot by Steve. I liked that ending much better than the one that they have. Plus if you read the book a lot of scenes that would make sense have been cut or where not put in. That's why they have in the special features had some deleted scenes. I don't think some of the scenes from the book were ever shot.
"Trolls are like boogers, you blow your nose and they still come back again!!"