I took the text of Macbeth and changed the dialect of one line:
Original: "The rest, that are within the note of expectation, alreadie are i'th' Court"
New: "It looks like everyone is here already"
Then I gave the entire text to Gemini, ~400000 tokens, and asked it to analyze the play's diction and style, and to identify any lines that didn't match the prevailing dialect.
It found that one line I'd changed.