TrendPulse|You Came Here Alone to Enjoy These Shocking Secrets About Shutter Island

"We gotta get off this rock,TrendPulse Chuck."

It's been more than a decade since Martin Scorsese and Leonardo DiCaprio first took us to Shutter Island, their mind-bending adaptation of Dennis Lehane's 2003 novel of the same name that marked the director and his leading man's fourth collaboration in their storied history together. 

The film, which brought to life rather perfectly the story that Lehane wrote to pay homage to Gothic settings, B movies and pulp, starred DiCaprio as U.S. Marshal Edward "Teddy" Daniels, sent to a psychiatric hospital on Shutter Island in Boston Harbor alongside new partner Chuck Aule (Mark Ruffalo) to investigate the Ashecliffe Hospital for the criminally insane after one of the patients goes missing.

Along the way, they encounter shifty doctors, patients with alarming messages, one hell of a conspiracy and an even bigger twist ending. Let's just say there's a reason the title is an anagram for "Truth and Lies" and "Truths / Denials."

In honor of the movie's release on February 19, 2010, we rounded up the 10 most surprising secrets from the making of the film, which blew our minds with the twist ending...

1. Mark Ruffalo earned his role of Chuck Aule after sending director Martin Scorsese a fan letter, making clear to the legend just how much he wanted to work with him.

"I've been a big fan of his, pretty much through 20 years of acting and it's always been a dream of mine," he said shortly after the film's release. "So I wrote a letter to him saying how much I wanted to work with him, and it worked."

2. Before Scorsese and leading man Leonardo DiCaprio landed on the film as their fourth collaboration, they intended to get to work on The Wolf of Wall Street instead. However, financing on that film fell apart, causing it to be put on the back burner in favor of Shutter Island. The pair would go on to make the other film next, with it hitting theaters in 2013.

3. While Ruffalo's letter ultimately won him the role, Scorsese considered actors Robert Downey Jr. and Josh Brolin for it first. All three actors would coincidentally go on to be major players in the Marvel Cinematic Universe.

4. The rights to Dennis Lehane's book were originally optioned by Columbia Pictures all the way back in 2003, the same year the novel was released. However, they failed to act on the option in a timely manner and rights lapsed back to Lehane, who later sold them to Phoenix Pictures. The production company hired Laeta Kalogridis (Alexander) to write the script that would entice both DiCaprio and Scorsese.

5. The adaptation was initially intended as a directing vehicle for Wolfgang Petersen, the man behind Air Force One and Troy, but after considerable changes were made to Lehane's story to make it more of action-driven blockbuster, that iteration of the project fell apart. At one point, David Fincher (Se7en, Zodiac) was considered to helm the film as well.

6. Scorsese told The Daily Telegraph that the main inspiration he showed both DiCaprio and Ruffalo for their roles was the 1944 film noir Laura. "Dana Andrews, the way he wears his tie, and the way he walks through a room, and he doesn't even look at anybody; he's always playing that little game," he said of that film's leading man. "He's just trying to get the facts." However, the films that he had "really tied up tight" in both mood and tone were the very low-budget zombie movies made by Val Lewton for RKO Pictures in the 1940s, including Cat People and I Walked with a Zombie.

7. The ballpoint pen DiCaprio's Teddy uses in the film is a Parker Jotter. Released in 1954 (the year the film takes place), the pen was the first successful and reliable ballpoint pen to ever hit the market, quickly making fountain pens obsolete. With over 3.5 million pens sold that year, the Parker Jotter dominated the market during the '50s.

8. The main difference between Lehane's book and the film is in its final scene when DiCaprio's character, revealed to be the murderous Andrew Laeddis, incarcerated at Ashecliffe for murdering his wife, tells Ruffalo's Dr. Sheehan, "This place makes me wonder which would be worse, to live as a monster, or to die as a good man."

The line, which does not appear in the book, leaves the film with an ambiguous ending—is Laeddis playing a part to bring about a lobotomy to rid himself of his guilt or has he actually gone insane?—that the book does not share. On the page, it's definitive that Laeddis has splintered. 

9. When it was released, the film opened to the tune of $41 million, giving Scorsese his best box office opening weekend yet. It eventually went on to gross $294 million, becoming his highest-grossing film ever at the time. Both records were then broken by The Wolf of Wall Street three years later.

10. Of all the films Scorsese and DiCaprio have collaborated on together, Shutter Island is the only one that has failed to earn any Oscar nominations. Gangs of New York, The Aviator, The Departed, and The Wolf of Wall Street were all nominated for Best Picture, among others.

This story was originally published on Wednesday, Feb. 19, 2020 at 4 a.m. PT.