Hidden clue in classic Leonardo DiCaprio movie has people saying it’s 'one of the most unexpected plot twists' they've seen

Leonardo DiCaprio is one of the biggest actors in Hollywood, starring in some of the biggest movies on the planet.

From the classic that is Titanic to of course his iconic role in The Wolf of Wall Street, choosing the 49-year-old's best flick is a tricky one.

Another one of DiCaprio's films, perhaps a little less known than the others, is Shutter Island.

The 2010 release saw DiCaprio reunite with legendary director Martin Scorsese, who he'd previously worked with on Aviator, The Wolf of Wall Street and Gangs of New York.

The pair teamed up with Mark Ruffalo and Ben Kingsley for Shutter Island, in which DiCaprio played a US Marshal sent to a remote island to investigate a missing patient - or so we thought.

Those who have watched the movie will know what goes down, but even to this day film junkies are noticing new things.

One particular detail was brought to the attention of many fanatics by an account that goes by the name of 'Creepy.org' on X, formerly known as Twitter.

Had you spotted the detail? (Paramount Pictures)

"In 'Shutter Island' (2010), every time Leonardo smokes in the film he gets his cigarettes lit by someone else. This shows he was a patient because mental patients are not allowed to have matches," they wrote.

Many fans have since flocked to the comments section of the X post after making the revelation.

"Thats an insane attention to detail and makes the film even more beautiful." one user penned.

"For me, Probably one of the most unexpected plots twists i've seen in a film," a second penned.

A third wrote: "this movie has one of the highest repeat value." While a fourth disagreed: "Actually, it doesn't have a repeat value at all. One can watch the scenes to experience amazing filmmaking but it doesn't hit it like 1st viewing!"

The film is well-liked enough by fans, earning an audience score of 77 percent on Rotten Tomatoes.

Leonardo DiCaprion in Shutter Island. (Paramount Pictures)

However, the flick is not Scorsese's favorite, as he revealed in an interview with GQ.

Scorsese explained that Shutter Island came to fruition after his 2006 film movie Departed earned him an Academy Award for Best Directing.

The win 'encouraged [Scorsese] to make another picture with Shutter Island - but that was not the smartest move.

"It turned out I should have gone on probably to do Silence," he said.

Silence, which was released in 2016, starred the likes of Liam Neeson and Andrew Garfield.