Board Thread:Manga/@comment-5774380-20151009004044/@comment-26932251-20151009051851

Hold on, I just read the wiki page for this chapter. It says that Erwin observes his prosthetic arm in the "they're not the only ones with something to hide" sequence, but the panel is focused on Erwin's left arm but it is Erwin's RIGHT ARM that was lost, not his left, so the thing (which is also prominently visible a page beforehand in the top panels) on Erwin's LEFT ARM is not the attachment for a prosthetic arm but something else completely.