All There in the Manual: Only some rules of the Long Walk are mentioned, but the ones that get the most mention are Hint 13 (conserve energy whenever possible) and Rule 8 (no interference with other Walkers).
Alternate History: A blink-and-you-miss-it example where Garraty narrates about a landscape view reminding him of the German air-blitz on the American East Coast during the last days of World War II. Other examples include a comment about an official who lost a leg to radiation storming a German nuclear bunker in 1953, suggesting the war went on for around another decade, and a mention of April 31 as the day before the Walk begins.
McVries seems to have feelings for Garraty that extend beyond friendship at times. At one point, he asks Garraty "Would you let me jerk you off?" Although his relationship with Priscilla would make it closer to ambiguously bi.
Also, Garraty. After all, he doesn't exactly say no when McVries offers to jerk him off. The opposite, in fact. He says "Whatever you want". That's practically an invitation.
Day of the Jackboot: The United States has been turned into a dictatorship after the second world war ended in a stalemate and the US fell into a renewed depression as a result.
Deadly Game: One hundred teenage boys are selected to participate in the titular "Long Walk" and only one is left alive by the end of it. Assorted remarks by the Walkers indicate that very few, if any, of the winners live long enough afterward to enjoy the Prize.
Pete McVries. He once had a romantic relationship with a girl that fell apart due to financial differences between the two and this is the reason he signed up for the Walk in the first place. Pearson even wonders how badly McVries wants to die.
Pearson: Jesus, what do you think? He oughta be wearing a 'BEAT ME HARD' sign. I wonder what he's trying to make up for?
Garraty becomes one by the very end. He's so mentally and physically worn-down by that point that he only wants to keep walking, and thinks his prize will be his own death. A dark figure then appears to guide him on, who may or may not be The Grim Reaper.
Determinator: What you have to be to even make it to the halfway point, let alone win. A particularly gruesome example is Hank Olson, who makes it just past the halfway point entirely on sheer force of will as both his body and his mind had completely broken down by then. He even gets shot through the gut and that doesn't immediately faze him.
Disappeared Dad: Garraty's dad had negative views against the government and was very vocal about it, going so far as to take Garraty to see a Long Walk when he was younger so that Garraty could see how horrible it was. He was ultimately "Squaded," slang for being taken away by the Squads and possibly Released to Elsewhere.
Face Death with Dignity: Scramm, knowing full well he can't finish the Walk with such an advanced case of pneumonia, and Mike, one of two Hopi brothers who gets struck with severe abdominal cramping. Instead of just falling over and taking it, Scramm says his goodbyes, talks with Mike who bids goodbye to his brother, and walks into the escorting half-track's path. They flip the half-track off, insult the soldiers approaching them and sit down to talk while they wait for death.
Get a Hold of Yourself, Man!: When Garraty experiences a fit of laughing madness and incurs three Warnings during said fit, McVries intervenes, holding Garraty up to keep him going so he doesn't get a ticket and attempting to verbally coax him out of it. Eventually, McVries slaps Garraty to get him to snap out of it before he gets his ticket, getting himself a Warning in the process of this act.
Go Out with a Smile: Pete McVries When he feels he can't go on for much longer, he sits down in the road and smiles at Garraty as he is shot by the soldiers.
Heroic Vow: Once word gets out among the Walkers that Scramm has a pregnant wife after Scramm himself is going to die, they make an agreement that whoever wins the walk will help his newly made widow.
Jerkass: Gary Barkovitch. Not only does he manage to make enemies out of most of the other Walkers, but he even manages to goad an already-enraged and violent Rank to exhaust himself, resulting in his elimination.
Jerkass Has a Point: As unpleasant as Barkovitch is for the most part, he points out that Scramm shouldn't have entered the Walk if he had a kid on the way.
Kill 'em All: Every contestant save for Ray Garraty dies during the Walk, and it looks he won't have long to live either, even though he won. It's mentioned earlier in the story that most of the previous Walks' winners died not long after due to the immense physical and psychological strain it placed on them.
Killed Offscreen: Obviously, a lot of non-characters among the boys get this treatment, but two of Garraty's friends are also unceremoniously offed out of sight or between chapters: Harkness, and much later, Pearson.
Meaningful Name: Barkovich. Taking "Bark" or "B...i(t)ch", his name helps paint him as a rabid dog—which he is most prominently when he provokes another boy so much that the kid buys his ticket, and again when he rips out his own throat.
Never a Self-Made Woman: The only girls and women who are mentioned (especially by name) or appear in the plot action are girlfriends and family members of the Walkers, who are all male. Justified, though, because the Long Walk only allows male teenagers to compete and the plot is basically the events of the Walk.
Garraty: God's garden? What about God's garden, Olson?
Olson: It's full. Of. Weeds.
Olson: I don't. Want. To die.
Pyrrhic Victory: Garraty is the Pyrrhic Victor of the eponymous Long Walk by virtue of having outwalked 99 other male teenagers. However, he's also watched most of them die, including those he had established a rapport with, and is at the point where his physical and mental health have greatly deteriorated and he welcomes the prospect of his own death.
Raging Stiffie: Gribble, who feels up a young woman watching the walk. The sexual frustration is enough to slow him down sufficiently to incur his ticket.
Rasputinian Death / Body Horror: Hank Olson is shot in the belly as he climbs up onto the halftrack. The next two bullets knock him to the ground, then he takes three more, and then he starts to sit up. More shots lay him out, but he manages to get to his feet and start walking - even though his intestines are now spilling out of his body. After he finally falls dead, the soldiers put two more bullets in him and take him away.
Released to Elsewhere: At the beginning of the book, all the reader knows is that if a Walker commits any offense, then they get a Warning and if he commits one more when he's already got three Warnings accumulated, he "buys a ticket." It then turns out that "buying a ticket" is a euphemism for being shot dead by the soldiers on the escorting halftrack.
Sanity Slippage: Practically everyone suffers from this at some point. Or at least, those who survive long enough do.
Suicide Attack: Hank Olson and Collie Parker both try to overtake one of the escort half-tracks by force. Both of them fail, but while Parker gets off lightly, Olson is made an example of.
Someone to Remember Him By: No one featured directly in the plot gets pregnant with or is one of these babies, but Scramm has a wife who is pregnant with his baby and with his death has made the baby an example of this trope.
There Can Be Only One: There is no set distance for the Walk. It just goes on until there is only one survivor.
Too Dumb to Live: A walker who dies early on was wearing sneakers, despite the rulebook that the contestants were given in advance explicitly telling them not to do so, as no other type of footwear will cause blisters faster on long distances. Predictably, he develops blisters after only two miles, and is ticketed after the pain becomes too great for him to maintain speed. Garraty even discusses it in his internal monologue, and Barkovitch derides Ewing for it out loud.
One might argue that this trope applies to Percy What's-His-Name as well, as he tries to sneak away from the Walk under cover of darkness. Of course, it doesn't work—the soldiers have sophisticated tracking equipment. They shoot him as soon as he leaves the road, and Percy should have known that would happen.
"Well Done, Son" Guy: Stebbins reveals that he is the illegitimate son of the Major and therefore, he only expects his "Prize" to be for him to "be taken into [his] father's house" and acknowledged as the Major's son.
Why Don't You Just Shoot Him?: Averted. The soldiers on the half-tracks have no problems shooting Runners under any circumstances, although they still have to give out the mandated three warnings unless the Walkers directly attack the vehicles.
An interesting example with Olson, who has bought his ticket and been shot multiple times in the belly to the point where his intestines are spilling out, but hekeeps right on walking. After he finally falls dead, the soldiers shoot him a few more times for good measure and then carry him off.
It's notable that most of the kills the soldiers deal out are quick and clean, but it's remarked in the story that because Olson confronted the soldiers directly, his death is deliberately drawn out so that other Walkers will think twice before trying to confront the soldiers as well.
Several Walkers pass out on the road, but the the soldiers still stand there and give the unconscious bodies their three warnings before shooting them. Rules are rules, after all.
One Walker ends up having his feet run over - and obliterated - by the halftrack. The soldiers still call out his warnings over his screams, despite the fact that there is no way he can continue.
Your Head A Splode: The very first elimination gives everyone a good idea of how serious the rules of the competition are.