The heroes actually managed to save Ibara from the ritual, unlike Asia in canon, but she needs to be reincarnated anyway to save her life because she took a light spear meant for Izuku.
Mizu used to be a successful Pro Hero before she suffered a Game-Breaking Injury, and those who were close to her back then can remember how depressed she was before she traveled to Kamar-Taj.
It's later confirmed that she was attacked by Stain, and Ingenium's attack has caused her to have nightmares.
In this universe, Mirio is offered One For All, but turns All Might down, wanting to become a hero on his own terms. While All Might respects and even admires his decision, it's further strained his relationship with his former sidekick, Sir Nighteye, who has been grooming Mirio to become All Might's successor, not realizing that One for All is acurse for people who already have a Quirk.
When Mirio appears in Chapter 49, he mentions interning with another hero due to the "difference of opinions" he had with Nighteye.
It's heavily implied that the Nomu was made from Riser and Ravel's missing brother in this continuity, and though Kyoka tries to reassure the latter that it could just be a coincidentally similar Quirk, it's clear that she's rightly disturbed at the thought of her brother being made into such a monster.
A later outright confirms this, also making it clear that any of his personality is gone.
Milia's parents were killed by Sieg, apparently right in front of her, despite having been living a peaceful life with their daughter. If Kudelia hadn't taken her in as a favor, she fully believed that she'd be homeless, since even then she often had to be reminded to do things like eating or going to school, and it took Izuku going out of his way to help her to get her to start moving past being a complete Broken Bird. When recounting her backstory to the exorcist group, she's so clearly emotionally distraught just by remembering it that even Xenovia, who is still heavily anti-devil at this time, is affected by it.
Lailah giving a speech to Irina and Xenovia, driving in the harsh truths about their faith.
Endeavor believes that the reason that Shoko prefers to hide her gender is that she developed a fear and dislike of other women after what happened with her mother, remembering how long it took her older sister Fuyumi to get her to become comfortable being in the same room with her. Even now they're not as close as they once were.
Izuku and some of the girls run into Eri, who is terrified after having escaped from Overhaul. Meanwhile, the cloaked figure is watching, wishing she could just go up and talk to them, but knows that the time isn't right.
She is terrified of doctors due to everything Overhaul did to her, causing her to shake in fear when she's at the hospital and hide under the bed.
Everyone is clearly worried about Iida in the aftermath of Stain's attack on his brother.
Despite Kiba's warnings on how Vengeance Feels Empty, Iida isn't able to let go of his hatred towards Stain.
When Izuku and Milia are on their way to Ryukyu's agency, they find a girl named Fuyuko about to commit suicide by jumping off of a bridge, and only narrowly managed to save her in time.
In the next chapter, we learn that she's from Shujin Academy, which is just as bad as it is in canon, and the volleyball teacher trying to force her to have sex with him, after several other cases of abuse that were dismissed by the principal, Fuyuko made her decision to commit suicide both to escape it and in the hopes that someone would realize that something was wrong and investigate the Sucky School.
Itsuka learns that she's half-devil... from Lailah, who chases her through the city trying to kill her. She ends up joining the fight against Stain while also dealing with Lailah, and after that, the Winged Nomu tries to kidnap her, only to be saved by Stain when he kills it. All within the span of maybe an hour.
Itsuka never knew her mother and was left in foster care after her father died in a fire, leaving her with no answers regarding her Devil heritage. Even worse, it's implied that at least some of this might be Fake Memories. A few chapters later, it's revealed that she did know her mother, who was a member of the Asmodeus clan and was attacked and seemingly killed in that fire. The seals on her memories and powers were her mother's work, in an attempt to keep her safe that nearly backfired.
During the Khaos Brigade attack on the Peace Conference, Creuserey Asmodeus brings out Itsuka's mother, controlled via a slave collar, and orders her to kill Itsuka. Itsuka accidentally frees her mother from the control, but only for long enough to allow the latter to commit an Heroic Sacrifice, barely giving Itsuka a few seconds to mourn her mother before she has to get back into the fight.
The Black Knight, when fighting Izuku at a museum they're (seemingly) trying to rob, gets under the latter's skin by giving the boy a speech about he's still just a weak little boy hiding from his own mediocrity, and that he'd likely be long dead if he'd never met Rias.
Ravel learns that her brother really was the Nomu that attacked the USJ.
Twilight Healing fails to heal All Might. Ibara is shocked that it happened.
When Stain attacked Mizu, not only did Ochako see how miserable her mentor figure was, but her parents lost their blacksmithing business because Mizu couldn't help with the payments anymore.
Although Izuku helps her pretty quickly, Kunou ends up separated from her mother Yasaka at Tokyo Disneyland, and the former was crying while the latter was clearly deeply worried.
Sirzechs telling Izuku how, even though he wanted to, he was unable to annul the betrothal between Rias and Riser himself due to political complications.
Ibara learning from Azazel that the Church likely screened the people that she healed so that she wouldn't run into anyone with an ailment beyond Twilight Healing's capabilities to repair deeply affects her, and Izuku has to go on a walk with her to calm her down.
When Gasper and his companions are captured, one of their captors destroys the Switch Izuku gave the half-vampire to make a point.
Magnus, a mercenary working with the magicians attacking the conference, manages to get under Rias' skin by preying on her insecurities over whether her calling her peerage her family is just a way to ignore her guilt in stealing her peerage's humanity. While she does manage to rally and take Magnus out, it's obvious that their encounter has left a mark on her.
Itsuka finds out that her mother Lasha is alive... when her uncle, who's put his sister under mind-control, tries to make her help kill her own daughter. Lasha is able to resist and save Itsuka but ends up fatally wounded herself in the process, with the only comfort being that she got to see her daughter one last time and die with a smile on her face.
She later turns out to somehow still be alive, but unconscious, with no guarantee that she'll ever wake up.
Osanne turns out to be a Khaos Brigade spy, and the one behind the Excalibur plot, and it's clear that the exorcists are hurt by her betrayal.
