Character mistake: Scarlett says that since McCullen is from Scotland, he speaks Celtic. Celtic is a group of languages, not a language unto itself (something a genius like Scarlett would most likely know); it would be like saying someone speaks Semitic or Germanic. McCullen would probably speak Scots or Scottish Gaelic, the official languages used in Scotland.
Character mistake: Stormshadow is a Japanese American, but in Snake-Eyes's flashback set in Tokyo, Japan 20 years earlier, Stormshadow calls out "Do dook nom ee dah," which is Korean translated to "Thief!" when he spots Snake-Eyes. (00:43:25)