Trivia: When Teddy enters the lighthouse, as soon as he begins to climb the spiral stairs, the camera follows his movement from in front of him. However, as Teddy and the camera wind around the stairs, the wall behind also appears to move with them, as though what is REALLY moving is only the staircase itself, rotating on its central axis. Yet another point (added to the various disappearing glasses/bottles) that adds to the general 'insane' feel of the film.
Trivia: During the ferry approach at the start, we are shown Shutter Island. In actuality this is a combination of Peddocks Island (the decaying brick buildings), Maine's Acadia National Park, Massachusetts' Medfield State Hospital, and Turner Hill Country Club's Rice Estate (located in Ipswich, MA), which were combined via CGI. Additionally, the mountainous region of the island (shown as the ferry approaches) was also CGI, and added in post-production.
Trivia: The scene where all the soldiers are shot along the fence is historically accurate, though there is debate on the exact numbers.
Answer: I think Mrs Kearns is in on it. We see her get a little flustered when she is asked about the doctor, who we find out later is sitting right there. Also, she gets uncomfortable when Teddy brings up Andrew Laeddis. She even tries to warn Teddy. I just discovered this recently when watching with the subtitles, but when Teddy comes back from the cave, Mrs Kearns can be heard saying "I can't remember what I'm supposed to remember", likely referring to the script she was supposed to stick to.
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