Ep.10 “Where’s the Left Arm?”

What are “Their memories”?

Q, Surrounded by the Garrison Regiment, Eren transforms a part of his body into the Titan and protects himself along with Mikasa and Armin when Captain Kitz Woermann shot with a cannonball to them but just before that, Eren remembered his father’s words that Grisha said. “This power will help you then! Their memories will tell you how to use it.”
What are “Their memories”?
In vol.3 ep.10 “Where’s the Left Arm?” (anime 1st ep.9).

A, According to Eren Kruger, “they” are the heirs of successive intelligent Titans. It suggests that the intelligent Titan will be inherited by the next successor, and that “memory” holds an important key to the story.
In vol.22 ep.88 “The Attack Titan” (anime 3rd p.2, ep.9).

Grisha said, “If you want to save Mikasa, Armin, and everyone…”

Q, Grisha told Eren, “If you want to save Mikasa, Armin, and everyone, you must master this power”
In vol.3 ep.10 “Where’s the Left Arm?” (anime 1st ep.9).

A, Kruger says something similar to Grisha. Rather than Grisha → Eren, it may be transmitted through the route of Grisha → Eren → Kruger → Grisha → Eren.
In vol.22 ep.88 “Meeting” (anime 3rd p.2, ep.9).

Ep.11 “Response”

Reiner that reacts to steam

Q, Reiner reacts to the vapor of Eren’s Titan, which blocked the cannonball and goes to see the situation quickly.
In vol.3 ep.11 “Response” (anime 1st ep.10).

A, It suggests that Reiner is a spy. He’s dying to know the information about Eren’s Titan right now.

Ep.12 “Icon”

Why do Titans appear from the south?

Q, According to the Survey Corps report, Titans were said to appear from the south, but why?
In vol.3 ep.12 “Icon”.

A, The “Borderline” is located in the south of Paradis Island, which is called “Paradise”, and people who are dropped inside from the embankment there are turned into Titans, and they head north in search of humans.
In vol.22 ep.87 “Borderline” (anime 3rd p.2, ep.20).

The three walls / Source: Attack on Titan

Who are the two figures?

Q, Who are the two people in front of the building in the back when Titan Eren attacks Mikasa?
In vol.3 ep.12 “Icon”.

A, Could it be Zeke and Eren taking a memory tour of Grisha?
No, probably not. This is because the memory tour is a journey through the brain, and it is not something that allows you to travel back in time to the actual past.
It must have been written with Isayama’s sense of fun.