Battle in the Center of the Mind: More of a struggle, but Shigaraki is currently doing so against his [former] master. It's clear since the Jaku battle that he's not at all interested in being a puppet.
The Bus Came Back: Muscular, Moonfish, Overhaul, and Stain are all seen again during the Tartarus breakout.
Call-Back: All Might vowed that All For One was never going to escape from Tartarus. AFO believes he was right, so he "synchronized" with Shigaraki to find a way out.
Downer Ending: Hundreds to thousands of Villains from various prisons are set free and already wreaking havoc across Japan while Shigaraki, All For One and the other League/PLF heads go into hiding. Meanwhile, many of the U.A. students and teachers have started to recover but are unable to yet deal with the mass Villain attack, and Midoriya is currently comatose. Through all of this, citizens are up in arms, demanding answers from their No. 1 Hero Endeavor, who is slowly recovering himself.
Great Escape: "Synchronizing" his own personal consciousness with the one controlling Shigaraki, All For One attacks Tartarus Prison inside and out to escape, bringing the other inmates with him. He then sends a handful to seven additional prisons throughout the country to free those Villains.
Innocuously Important Episode: The purple-haired woman as one of the Tartarus inmates was shown in the opening since "Hellish Hell", with her role and Quirk only teased. Who she is and why she was imprisoned in the first place won't be revealed until later.
Ironic Echo: Whereas Midoriya narrates at the start of the series that his story is how he became "the world's greatest Hero", AFO declares his story is how he will become "the world's greatest 'Demon Lord'".
"It" Is Dehumanizing: One of the guards expresses his distaste for all of the inmates in the prison, stating that they are nothing more than "monsters and animals", even the ones who are still human.
Jerkass Has a Point: The guard's view on the prison inmates borders on Fantastic Racism, but we have seen how utterly dangerous and remorseless some were in previous seasons. He may not be wrong in labeling a few as "monsters", though his assessment even extends to the seemingly kind-hearted purpled-haired woman who helps Overhaul escape, as well as Stain, showing that it's not correct to tar everybody with the same brush just because they all wound up inside Tartarus.
No Honor Among Thieves: Moonfish has no problem going through his fellow inmates to kill the guards and escape.
No Prison Segregation: The woman shown as one of the Tartarus inmates implies that it keeps Villains of any and all genders incarcerated.
"Not So Different" Remark: Todoroki wakes up in Central Hospital and processes the Jaku City battle and the fact his oldest brother is alive after all these years, but is now a Villain consumed with hatred against their father Endeavor. Remembering how Todoroki acted back then before Midoriya set him straight, he realizes that Toya/Dabi represents the "past" version of him if he never let go of that resentment.
Todoroki: Toya... is me.
Out-of-Character Alert: Spinner notices so many things wrong with Shigaraki ever since they left Jaku City. Retreating from battle, leaving behind the other Leaguers, talking as if "Shigaraki" is somewhere else. He outright states that this isn't the same man he chose to follow back then.
The Unreveal: All For One sends several Tartarus escapees to break into seven additional prisons, but only six worth of inmates are said to be roaming free. What happened with the seventh prison is currently unknown.
We Need a Distraction: AFO invokes this by instigating a mass breakout of 8 total prisons, keeping the Heroes busy while Shigaraki recovers.
