A bit of narration near the start of the book has Rico reflecting on how he gets the shakes before every drop. The doctors have looked him over, and informed him that nothing's wrong with him. They reassure him that this isn't fear, but rather excitement, like a race horse in the starting gate, rearing to go.
The Thirty Second Bomb. In a fighting force that routinely uses Flame Throwers and atomic weapons in combat, this is the weapon that Rico feels bad about using. It is designed to loudly announce in the target's native language that it is a bomb, and then issue a loud verbal countdown to induce an appropriate response. Rico causes a stampede by tossing it into a Skinny command center.
Rico's Un-Paused moment late in the book. He is protesting his commander's decision to use a post-hypnotic suggestion to make Rico take a nap. His commander doesn't seem to know what Rico's going on about, and Rico soon realizes that he was put to sleep halfway through a sentence, waking up hours later and continuing without missing a beat. Nevermind the humorous situation of a Space Marine refusing (futilely) to take a nap.
This line would be even more funny if it didn't lead to tragic consequences for Zander later on.
Carmen:(after giving her location to Rico) The situation is... (takes a look around to see that they're surrounded by bugs) Situation is extremely hostile!
Carl and his pet ferret Cyrano, "Go bug Mom!".
Carl: I gave him the impression that there's a grub crawling up my mothers leg, he's on a mission to go eat it.
Carl's Mom: (banging noises can be heard upstairs) What are you doing?! GET OFF MY LEG!! AWWWW! ...Carl!
Rico: (as the lights go out and sappy music starts to play) Uh oh.
The Tanker Bug's Aside Glance to the camera before getting blown up by the grenade it swallowed.
After Carl's reading of the Brain Bug's mind, Rico and Carmen catch up to him.
Rico: It was you wasn't it. You told me how to find Carmen?
Carl: (gives a smirk) Well, that's classified.
The last we see of the Brain Bug is getting probed by human scientists, and evidently inflated.
Many of the scenes satirizing military jingoism and literary and film warfare tropes are darkly humorous. Standout examples include the ludicrously harsh and unsafe bootcamp, the coed showers in the same, the absurd Hollywood Tactics the Mobile Infantry employ, Lt. Rasczak rewarding his troops with what are essentially children's toys, and the "new meat" the now-grizzled protagonists critique at the end being children in their early teens.
Although the toys can be Truth in Television. When you're bored, a pick-up game of football can be hugely popular. Also, war is about 98% boredom (and 2% heart-stopping terror).
Fairly early on, a propaganda bit shows that, if the soldiers shoot a specific point on the bug torso, it will drop the bug instantly. Once this bit is seen, the viewer is given scene after scene after scene, throughout the entire movie, of troopers failing to heed this one piece of advice, and each bug taking one clip or more of ammo to be put down. While it's allowable during the massed assaults by the bugs where it can be difficult to keep calm and fire straight, the situations where it's a squad versus a single bug, and the bug is clearly winning, the absolute incompetence of "ivy-league hopeful" Rico and his even less-intelligent comrades is on full display.
However, it's similarly absurd that the propaganda short indicates that knowing about that weak spot will do anything to help anyone, since it's a thumb sized node on a fast-moving creature twice the size of a cow. No amount of marksman training will help most people hit a target that small in a live battle, and about the only sound tactic would seem to be lobbing/launching grenades at it's underbelly and hoping some shrapnel takes it out (kind of hard when your army has no stepping stone between "assault rifle" and "portable nuke"). Seeing Johnny's old friend act so smug about how easy the fight's gonna be with knowledge of that "glaring disadvantage" is just icing on the cake.