Moglin introduces himself to the group, explaining his name and nickname (MOOGLE or MOG) are both acronyms, so the cadets can call him what they like. Cinque names him "Moglin." Moglin protests that he has a real name — "Hatzkhaminei Lowtoyosna Eripulci." Cinque decides that's too long, Moglin is good enough.
The order for Code Crimson in Chapter 4, 'Mission Under Ceasefire', is exactly that - a mission during the tripartite ceasefire. Upon arriving in a mountain to back up some Imperial troops having trouble with local monsters, we get this exchange.
Cinque: Hey, Imperial troops. (sneaky voice) Should we kill them, too?
Ace: We're in a ceasefire; they won't shoot at us. Leave them alone.
Cinque(sounding disappointed): Yessir...
And then, when you rescue the Militesi who were being terrorized by the snow giants, they make fun of Ace and Cinque (and presumably the rest of Class Zero, but just the two are in the cutscenes) for being so young despite being the infamous 'red demons'; then they burst out laughing, and Cinque laughs with them.
Cinque: Even the Empire has cheerful people, huh.
Ace: (incredibly uncomfortable expression that screams 'my face is not cute')
Black Comedy it may be, the conclusion of Chapter 6's mission, The Clash on Big Bridge: After Caetuna summons Alexander and everyone watches it slaughter the Militesi Empire, the narrator says "the Imperial soldiers that yet survived fled back across the border into Milites." Cut to Incognitus powering the magic shield on the MA Gabriel, with Qator inside. The two of them compose the entirety of 'the Imperial soldiers that yet survived'.
In Chapter 7 you have the option to talk to the class Tonberry in an optional scene, which as usual are marked as needing two hours of in-game time to do. The Tonberry says absolutely nothing, and after two or three dialogue boxes full of "...............", you get an item. At this point the developers are obviously and purposefully Trolling us.
This also gives the impression that someone in Class Zero actually sat down and listened(?) to Tonberry for two hours.
Nine bragging that he could name all four nations of Orience when Quon points out his stupidity.
On the subject of Nine, the Vermilion Bird statue in the Fountain Plaza is one of the 'scenery quote' locations, with two quotes available per cadet. Most of the Classmates Zero say something inspired around here; Nine just looks up and says, "That's a big-ass bird!"
In one village, you're tasked with tracking down a rare jewel that was stolen from the mayor. You eventually find out what happened to it — a Chocobo swallowed it. After you find this out, there's a fade to black, and you get the jewel back. The onlooking Dominion Legionary outright says, "You Class Zero cadets have guts!"
During the normal ending, when everyone is thinking about plans for a future that's never going to come, Cinque proposes plans for ten years later. Jack points out that they can't know what's going to happen in the future, so they should just "live in the now, you know?"
Seven: Oh, is that why I heard you whisper you never want to grow up?
During the secret ending, Sice works herself up to give a love letter to Kurasame. As she sees him coming down the hall, she closes her eyes, whirls around the corner with her head down, and holds out the letter. Cue Seven popping up between her and Kurasame, and Kurasame walking off as Seven takes the letter.
The first scene of Cinque talking about Ryid and how she has never seen such a big guy before, and getting lectured by Trey about it.
Put Cinque on point during Operation Vulturnus, when you run into the wingvern on patrol. This mission is Class Zero trying to get into Concordia's Royal Central Command unnoticed, so they've got to shoot down the dragon before it reports them, and thus everyone has a line for that. Cinque's line is "Massacre all witnesses!" in a voice that sounds like she's trying to imitate Sice.
If Cinque is in your party upon arriving at Pandæmonium, she doesn't speak during the break in Cid's Evil Gloating when the rest of them do, instead resulting in this exchange at the end:
Cid: Within my dark clutches, you shall die a slow death.
Even Cinque's attacks are funny. When she slams her mace down for Earthquake, she ends up falling on her rear too. If she uses Whirling Mace and the battle ends, she just continues spinning anyway.
Many of Jack's scenes.
The first time the class receives their COMM devices, Jack decides to test the line by saying that is exactly what he is doing. Queen is annoyed and tells him to keep the lines clear of his nonsense.
Even funnier, Queen proceeds to ask Seven on her status. If katana and whipblade showing up to help Ace do the Special Eidolon summon for Odin is any indication, Seven and Jack were in the same place, and Queen decided that, rather than let Jack keep talking, Seven could inform her of their status.
His Deliverance attack will cross a battlefield to get you within hitting range of an enemy inflicted with Killsight. Not targeting an enemy inflicted with Killsight? He trips.
This exchange during Tempus Finis, after Jack tells everyone to cheer up and picture a brighter future:
Made funnier because Trey starts by complimenting Carla on her being a great student and a kind soul.
Carla goes on to ask for an insane amount of gil for the seminar. When Cinque refuses, she calls her a tightwad and then immediately reverts back to being cheerful and pleasant.
Carla's scene with Jack and Cater, where she asks them to call her a 'Blazing Merchant'. She seems to also have dropped the nice girl charade a little bit here.
Cater: "Blazing Merchant"?
Carla: Yes! Because I'm always trying to blaze a path towards new customers! Defective personalities, even hungry children! (camera turns to Jack) Frivolous people? Certainly! (camera switches to Cater) Even arrogant people! I offer my goods and services to everyone!
Jack: Was I just casually insulted there?
Cater: Yeah, I sensed some spite, too.
And then she offers an energy drink for an insanely high amount of gil.
Ace is a Megane bookworm trying to get into higher education, and Machina is his best friend and trying to get him out of the Crystarium.
Sice's aforementioned crush on Kurasame is one of many female students' such attractions. Kurasame still wears his mask, and since Kazusa's experiments with the Ice Reaper's eyeball prove they have a model for him without it, one can assume that they had him keep it just because it's funny.
Eight seems to being tending an attraction to Cater, who's "I'm not Queen, I don't read stuff" attitude has bit her in the ass - and the grades. In an attempt to jump from (what used to be) Central Command to (the old location of) the great portal, she lands on Eight.
Jack, Trey, and King are in a band, and King refuses to practice on the grounds that "I play from my heart - my performance will be perfect". Trey takes the first opportunity to follow him and starts talking about a hot brunette working at a cafe. Jack eventually goes from "we have to practice" to "don't leave me behind". And Trey is still wearing his mitsugake.
Queen, Deuce, and Cinque are lacrosse players, and it would seem that Ace is dating Mutsuki. Deuce's horrified expression is sure to give a few shippers a field day, and Queen's gossiping attitude contrasts brilliantly with her wise studious behaviour in the main game.