I didn't get the whole big deal about the ending. It was a great movie, the hints of him being crazy, of his wife killing the kids, of him being in denial, of never having a partner named Chuck... are all over the place. I don't want to say it was predictable, but all the answers are there, and he built up to it very well. It wasn't like his madness just came out of nowhere just to fuck with our mind. If people felt there was some things left unanswered, they just need to re-watch the picture.

WTF?

1) He wanted to "blow the roof off the place." because of the lobotomising.
2) Dr may have found out his intentions and decided to forge a plan not to let him leave the island.
3) The 'real' Rachel warned him, he had hallucinations but never THAT bad. They said the lighthouse thing was all in his head, even though there was a promiscuous shot of the lighthouse right at the end
4) When he was interviewing one of the cops in his investigation, Teddy asked about the lighthouse and the cop paused ans then said it was for sewage, when he went in they claimed it was just an empty lighthouse.

I felt like lots of things pointed towards him being sane.. I had loads when I first saw it, memory has faded a bit now though.

_His wife was bleeding from her stomach when he dreamt about her, and she was always wet "Why wet baby"
_The wife whispering to him "The killer is still here"
_Actually showing the past, when he first talks about his wife on the ferry (5 minutes into the movie)... they're definitely telling us that THERE's where our story's going.
_The whole fantasy/surreal way the whole building was shot, before entering it. It's like, they're entering a haunted house.
_He actually imagined 3 children: 2 boys, 1 girl. If there was not children in his mind, he would've dreamt about silhouettes.
_When he was talking to this person in Bloc C, didn't you ask yourself "why is that crazy person so wise?"...

When you remember the story, the key shots were about his dreams and his period in the army. Nothing in these, didn't scream "insane" ...

Speaking of the army sequences...I didn't exactly understand how those fit into the movie. What am I missing?

It was all part of his made up fantasy world. He knew he experience something tragic, so he replaced with finding a concentration camp in his head.

Ah...ok. I suppose that makes sense.

Yup. That's where he imagined the girl and her mother dead. A girl, victim of the war, was accepted by his mind, and he thought that's where he should have saved her (what's triggering these visions).
And as a hero who liberated the concentration camps, Shutter Island was his next battlefield.

I think the signs in the film point more to a way to get you thinking about the movie enough to go see it again or buy it on DVD.

It was based on the book in practically every respect. The extra shots and extra dialogue is just achieving what the director and whoever else wanted to achieve... the sense of a twist after the twist. It is in this way that movies keep playing in your mind because you think you haven't found the answer yet. The story itself, as adhered to from the book, is simply the twist and nothing more.

You seem to be forgetting the entire point of the whole experiment: To make Teddy feel like he was really investigating a real incident. This would require involving certain figures in the scheme. Especially the guards, and certain other figures in the institute playing their role. If they had not been involved, they obviously would have just up and said "HEY! Get back in your cell you deranged fuck!"
You'll also notice that more towards the beginning of the movie, when Teddy is walking through the facility... people look at him knowingly. It's very easy to spot in several scenes... but you, as a first time viewer, don't notice it because you don't know the ending. Watch the movie again. You'll see things you missed.
Also, the range of ability an involved personnel can actually stick to the details is variable at best, and this is one of the reasons I liked the movie is because they stuck to the human aspect where one knows what he's "supposed to say" but can make an error. The movie uses this error to create what you're now sodomizing as an ending that only exists in your mind... because that's what makes money after the fact.

Hmm, well another one, if it's role play why did the woman whilst doing role play write RUN. I think I believe he's sane because there are some clues that point to that and I want him to be sane.

His wife said if you go into the lighthouse it will be the end of you, she was right. His first dream, when he wasn't pumped up with Cawley's pills, he dreampt about her in a building that was burning down..

It seemed like, how many patients were in there? How can you do role play for ONE person, fake guards wasting their time outside a lighthouse guarding it.

The children thing did confuse me, he had 2 boys 1 girl, why did he only focus on the 1 girl? When Dr Cawley showed him the pictures he said "you should know this one" (or something along them lines, memory has faded a bit.)