Board Thread:Manga/@comment-35417358-20161009053634/@comment-5774380-20161009142410

As I said:

"We need to wait for the next chapter and see what happens, this issue was pure flashbacks so it doesn't tell anything about the story. For now let's consider it as still part of the Return to Shiganshina and according to the events of the next chapter we'll see what to do."

Also, this chapter does have to do with the Return to Shiganshina, because the 58th expedition had two purposes: to seal the hole in Wall Maria and to find out the secrets of the basement, so this chapter could be considered as the conclusion of the mission.

Also, arcs always start and end with the volume releases and this was the last chapter of volume 21, and they usually end with an event that ties with the next arc, like the Female Titan arc ending with the Titans of Ragako and the Uprising arc ending with the preparations for the 58th expedition and Zeke's revelation, so there's no problem for this chapter to be considered as still part of the Return to Shiganshina.