Samwise Gamgee actor Sean Astin reveals that he once had to stop his limo for a Lord of the Rings fan who wanted to point out a movie mistake. The first Lord of the Rings movie, The Fellowship of the Ring, was released in 2001 to rave reviews from critics and audiences, with similarly positive reviews for The Two Towers in 2002 and Return of the King in 2003. The Hobbit trilogy, the first film of which was released in 2012, was successful at the box office but largely failed to capture the same magic of the original three films.

Director Peter Jackson was praised for his focused and yet epic storytelling and the way he honored the original Lord of the Rings books by J. R. R Tolkien. The Lord of the Rings films brought together a talented cast of actors, many of whom had yet to have their "big break," including the likes of Elijah Wood as Frodo, Astin as his loveable best friend Sam (though Astin initially rocketed to fame as a child actor in The Goonies), Billy Boyd as Pippin, Dominic Monaghan as Merry, and Viggo Mortensen as Aragorn, all of whom were propelled into superstardom. Since appearing in Lord of the Rings, Astin has appeared regularly in movies and TV, most notably as Bob in Netflix's Stranger Things season two.

Related: Lord of the Rings: Who Forged the Great Rings of Power?

In a Screen Rant exclusive interview celebrating The Lord of the Rings' 20th anniversary, Astin remembers one encounter, in particular, he had with a passionate fan. According to Astin, this fan took issue with the cave troll fight scene in Balin's tomb from The Fellowship of the Ring and how one element of the scene goes against what author Tolkien had established in The Hobbit novel. Check out Astin's full story below:

"And it's funny how, after a week of it, you're just used to it. You're just like, 'Oh yeah, of course, we're in another thing, we're in another thing.' But we jump in the limo and there's this guy knocking on the window because people were always like... It was like a Beatles movie, they were always chasing after you. It was crazy. But this guy, he was dressed fancy. So I rolled the window down a little bit, and he puts an envelope through the thing, and he is like, 'Hi, I'm Dr. So-and-so.' He's like, 'I have to tell Peter Jackson that there's a mistake, or there's an anomaly,' or something like that.

"When the cave troll comes into Balin's Tomb, and it's really the first time the Fellowship sets up as a group, and we're fighting him. I'm using pots and pans on orcs, and Elijah's got the mithril vest to stave off the orc, or the whatever, the cave troll stabs him with the spear. Well, Balin's Tomb, the dwarf is lit by a ray of sunlight, and the cave troll passes through it. Well, if you know the Hobbit, when trolls encounter sunlight, they turn to stone. This cardiologist had identified this seam in the universe, in the mythology where we had made this mistake. I just remember thinking, 'I don't think we can redo it now, man.'"

Frodo and Sam looking at the Black Gates in The Lord of the Rings: The Two Towers

Although Jackson clearly reveres the books, the sheer breadth of adapting such expansive and lore-intensive novels means that small mistakes and oversights are inevitable. Behind-the-scenes featurettes for the films also reveal the long, grueling hours Jackson put in to make the films, so it's not entirely surprising that something slipped through the cracks. Jackson himself, who also directed The Hobbit trilogy, would correct this mistake in An Unexpected Journey when three trolls are turned to stone as they sit around a fire deciding how to cook and eat Bilbo and his dwarf companions.

Ultimately, while fans who are familiar with the books might have been irked by the troll oversight, it would seem that most are overall pleased with Jackson's adaptation of Tolkien's novels. The Return of the King, for example, is tied with Titanic and Ben-Hur as one of the most awarded films ever at the Oscars. Amazon is hoping to capitalize on the continued love of The Lord of the Rings with their new series of the same name, which is currently in production and expected to release in the fall of 2022. Without Jackson's involvement and with production on season two confirmed to move from New Zealand to the UK, a first for any Lord of the Rings project, many fans are justifiably keeping their expectations in check.

More: Every Lord of the Rings & Hobbit Movie Ranked, Worst To Best