Shutter Island
This film may be known for the final twist, and most similar films have limited re-watch potential once a twist is known. Scorcese accounts for this beautifully. Even once DiCaprio's delusions are known, rewatches of this film maintain one's full, undivided attention.
On first watch, the viewer has no reason to doubt the reality presented before them. Why would they? The inclusion of Mark Ruffalo is tantamount to maintaining the audience's trust in the illusion because his partner couldn't possibly be in on it, since they arrived on the island together. The scene in the cave not only displays the extent of DiCaprio's psychosis, but also plays into the audience's expectations that there must be something else to this film. Of course, the doctors were experimenting on the patients; of course, it all makes sense now. That's why they were acting so suspiciously throughout. This scene lulls the audience into a false sense of security; everything is as it should be, our hero is going to save the day and free these people from Ben Kingsley's dastardly grasp. We see the island through Laeddis's eyes: a setup that complements the penultimate twist perfectly.
Upon rewatch, this film gets even better. Small details that were previously unnoticed or dismissed suddenly become apparent, and everything falls into place. Laeddis is the perfect unreliable narrator, and so everything in this film comes into question. Each scene is placed under scrutiny as though we were an orderly listening to Laeddis's tall tales of a man with mismatched eyes and nazi experimentation.
Scorsese may be remembered for his mob films, but this truly is his masterpiece.
If I was to sink my teeth into your eye right now, would you be able to stop me before I blinded you?