I had the same takeaways as
@ColyH, most telling the ommission of the heart-attack victim possible witness, and a few other thoughts on the documentary.
* "4 tracks" going up the hill was mentioned, but I don't recall detail...the tracks ending or circling back? As for Gary being thrown off a bridge and one of the 'boys' taking his shoes with them, I suppose it's possible. But unless there was a forced march w/o his shoes, or he liked to travel in his socks (in winter) he'd have had them on. So, my take is 4 walked up the hill for higher ground to see if there was a view of lights and civilization, Madruga staying with his car hoping for a passerby. If Gary was already gone the 4 remaining walked up. But if Gary was out of the picture I don't see them acting so methodically in what would have been a beyond traumatized state. As for all of them continuing forward instead of retracing the car's route, if they were threatened they might not want to turn back with or without Gary. They likely thought they'd find help by daylight. It is curious they wouldn't just stay with the car, but perhaps in trying to get back to it they got lost.
* Backing up, we don't know as fact the boys were "afraid" of Gary or didn't want him to come. It's possible he had gone off his meds but that's speculation. It's more sensical to me (if they even were conflicted in the first place) that it wasn't they were afraid of HIM, but of what kind of ruckus he might cause (or attract) with others at the game. If he'd been getting harrassed in front of them and became agitated/tempermental towards others (but not his boys) it explains the 'local bully' story offered. One scenario might explain part of what happened: If Gary popped off at someone/s or (more likely to me) came to the defense of one of the others' being targeted, things could've escalated. If Gary or one of the others was physically taken following a dust up outside of Behr's, I'd bet the others would follow their friend. "We'll let him go if you follow us." That's urgent, and immediate and they would likely follow right away rather than call police. In the time before cellphones, I think most people would as well. Don't lose sight of the car taking your friend/spouse/child away. It's also the simplest reason for them to venture seemingly w/o hesitation in the wrong direction, in the dark, without proper clothes, with no real sense of where they were going. Something big would make you do that. As for what bully would go to such lengths, to a drunken or drugged up guy with nothing else to do, that mileage might not seem like a big deal or was on his route anyway. Or more darkly, it wasn't random and someone had it out for Gary specifically for some undetermined reason...perhaps years past and drug-related. But that could've been taken care of w/o the others as witnesses though.
Chronologically, I think something happened at Behr's. The bully car led the Montego up. At some point, it pulls over and bully hauls Gary out of the trunk and drops him in the snow to go back to his friends. Either the boys drive further and end up in a snowbank, or, at Gary's release bully ousts Madruga from his car and slides it into a snowbank to make things more difficult (but not intending to have them all be dead within months). Prank over. Until it wasn't, because they didn't go back down the way they'd come. In real time, I don't think even Gary was thiniking "we better leave a note in the car because we'll all be dead soon." I'd be interested to know if there was a pen or pencil in the car.
* Fast forward, Ted was wrapped with his arms folded on his chest and the documentary said he couldn't have wrapped himself. So I believe he had already died and that was a casket like pose and shroud. The remaining friend/caretaker then left the trailer alone and with no plan. I think that friend was Jack. He and Ted would likely have been given specific instructions from Gary and while they opened some of the rations they didn't open the other food locker. Once Ted died, Jack left on his own with no survival skills, and made it a mile before hypothermia set in. In June in the mountains, still a very liekly possibility, especially in his own weakened state.
So why didn't Gary care for Ted and Jack? Because Gary had left weeks or months ago, intending to return with help asap. The trio might have hoped for rescue for awhile, but the frostbite would speed the urgency. Gary likely rested and ate, but would be the logical choice to venture out with past military experience. He'd also know there'd be a point where gangrene would cause action over waiting for help. At the trailer, he would know how to get the heat going, but perhaps wanted to avoid an accident if he left an already suffering Ted and Jack in charge of propane. He knew how to open the food and could have shown both Ted and Jack. Perhaps he did show them the other food locker but they never tried it or forgot his instructions. The half burned candle tells me it wasn't lit after Gary left or potentially at all. Maybe he had the only lighter/matches and took them with him. He would have known to take any flares with him. But maybe none of them had a fire source in the first place. It would helpful to know what else was (and was not but should have been) in the cabin supply-wise. Gary swaps his shoes for Ted's boots and sets out likely still in the snow pack. He would have had the wherewithall to follow a road if he could find/see it. But he's also human, weakened, underdressed and in the middle of nowhere. I think Gary is still in those woods and died like countless others unprepared for a national forest, through no fault of his own.
As for wild scenarios, does it make sense they were targeted because of their own game the next day? That seems beyond the realm but people are crazy, could others have known they'd be in Chico and followed them to Behr's? And lastly, I don't see it...but one could theorize they were taken to the trailer FIRST as some sort of ransom or joke. And the bodies were found as they made their way from rather than to the trailer, with the Montego being left by another party. That sounds unrealistic as well, but who knows. It'd be interesting to know if the window on the trailer was broken in, or out. I also wonder, since Jack's father was so deadset on finding his son, and mentioned the trailer to authorities, if he was told not to check it out himself...it seems like something he would have done.
Lastly the sighting of "Gary" at the bar, and I'm assuming here the witness truly believe that's who she saw...why would Gary return to the area? He'd either be considered a suspect (which he still is anyway), or possibly worse shunned for not helping his friends and escaping as a survivor. I think there is a chance some evidence of his demise could still be found all this time later.