Four hours into the exam and the Villains have four objectives in reach and the location of a fifth. Keep in mind that they need only five to pass - any others are just extra.
Perhaps one of the more stand-out moments is the first time things go wrong for Izuku. The Villains have accidentally triggered an alarm, and the Heroes are mere minutes away from arresting them. But with Izuku's orders and several "surprises", the villains held their own until reinforcements arrive; at which point Bakugou's plans quite literally go out the window.
Kingpin VS Paragon. Kingpin turns the fight into a Battle in the Rain and efficiently controls the flow of the battle; redirecting Paragon's explosions and destroying a gauntlet with his hat. Paragon has pretty much lost the fight after that and Kingpin uses the opportunity to deliver a brutal Curb-Stomp Battle and "The Reason You Suck" Speech:
Kingpin: You know, I find the irony here almost cathartic. Not because you're the hero and I the villain, but because this exercise has proven something Ive always believed. I know that you are obsessed with being "Number One." I know you think that heroism is a competition, that being the best means something. Being Number One? It never mattered in the same way to me. I appreciate the title, the meaning behind the words. There are heroes and there are villains. That's the fight you should worry about. Number One? It's a joke. A public opinion piece ran by gossip magazines that worry more about sales than merit. Id rather be a "Symbol of Peace."
Neito's Heroic Sacrifice involves him copying One For All and destroying part of the museum with an uppercut, bringing down the ceiling on top of the heroes. It gets even better when said sacrifice turns out to be all part of Midoriya's plan, though it happened slightly earlier than intended.
By the end of the above events, the Villain team has achieved the five objectives they need to pass and has found eight additional targets.
One for the Hero Team in chapter 26. For the first time since the start of the story, the Heroes have well and truly caught Kingpin off guard and attack the Villain base. In less than 15 minutes after the Heroes discover the location Todoroki, to whom Bakugo has accepted to forfeit command, makes up a very efficient attack strategy, which opens with him creating a massive wave of ice that seals almost all the escape routes.
It, however, turns around into another for the Villains, as they ultimately manage to escape with all the accumulated objectives and no losses while "killing" more Heroes. Of note are the actions of Deku, risking everything by taking on both Bakugo and Todoroki (even with the help of some special gear) to keep them occupied, and Shoji who single-handedly keeps Kirishima, Tetsutetsu, and Uraraka at bay and then "kills" a distracted Todoroki.
The real turning point of the battle is, naturally, Kingpin entering the fray. After taking the 14th objective, the villains are in bad shape - although they've taken no losses, they're boxed in by Todoroki's ice, heroes are swarming in from every angle and they have no clear means of escape. They need a distraction and a way out, so Kingpin straps on gauntlets armed with kinetic batteries, asks Pirate Radio to cue him some boss music and hurls a safe so hard it shatters a building entirely. He swan dives off the top of a building, dodges Bakugou almost mockingly, lands on the glacier and destroys it with a single punch. Like that, the Hero Team's momentum is gone and Todoroki and Bakugou have to deal with a Deku who is armored and stronger than ever.
Shoji manages to throw Kirishima, Tetsutetsu and Uraraka from the top floor of the tower they're on, "kill" Sero and Todoroki, whilst Kaibara is gleefully firing an anti-aircraft gun at absolutely anyone he can, Monoma is chucking pipe bombs in every direction and Mei proves a excellent sniper as the villains make their grand getaway, all while an instrumental version of Welcome To The Jungle plays from every functioning speaker.
Right at the start of the third day is when the Civil War Exam, just over 48 hours after the Villains Team started their assault, the hero students have been reduced to 6 out of 25! And the villains have 14 out of 15 objectives without a single casualty, effectively beating Endeavor's record (12 targets, while suffering 60% casualties)! And how does this all end? Betrayal. The final objective is for the villains to betray one of their own. So how does Midoriya pull it off? He waits out near one of the city's exits for what's left of the Heroes and then has Hatsume snipe him with one of their paint rounds. In short, the Villain team got a perfect score the only perfect Villain score in the entire history of the exercise!
And at the very end, Jiro reveals a device she had left behind to celebrate the victory: fireworks pop out of the Tower while Queen's We Are The Champions plays.
Even before the exercise starts, both groups pull off some Loophole Abuse:
The rules about not spying during preparation do not specify between the end of it and the beginning of the exercise, so the villains send a small group to retrieve info from the sleeping heroes.
The heroes recruit a few more people in their ranks thanks to the lack of some specifics about their school year. The Big Three (Mirio, at this point of the timeline, has still his quirk) are in the game.
It's the Darkest Hour for the heroes: almost half of them "killed", and some of the "survivors" are considering just throwing the towel. Then Bakugo comes and delivers a Rousing Speech that's likely to get their Heroic Second Wind out, while Deku figures out several countermeasures to get their reputation back up. In an interesting parallel, at the same time their counterparts are fighting each other instead, and the consequences may ultimately bring the villains down despite their current great advantage.