Warning: There are spoilers ahead if you haven't seen/read "The Martian."

"The Martian" is out in theaters Friday.

The sci-fi epic based on the best-seller by Andy Weir follows an astronaut stranded on Mars. But one of the stand-out moments of the film is from another literary great: "The Lord of the Rings."

About halfway through the film, as NASA's figuring out a way to bring astronaut Mark Watney safely home, engineer Venkat/Vincent Kapoor (Chiwetel Ejiofor) calls for a braintrust meeting between himself, NASA PR head Annie Montrose (Kristen Wiig), flight director Mitch Henderson (Sean Bean), director of the Jet Propulsion Laboratory (JPL) Bruge Ng (Benedict Wong), and NASA administrator Teddy Sanders (Jeff Daniels). Kapoor thinks he's found the one person with a viable plan, astrodynamiscist Rich Purnell (Donald Glover).

Donald Glover plays the man with the plan to bring astronaut Mark Watney home safe, astrodynamicist Rich Purnell. Fox 20th Century Fox Venkat decides to call the meeting "Project Elrond."

If you're a "Lord of the Rings" fan you may have chuckled.

The meeting refers to the Council of Elrond, which took place in "The Lord of the Rings: The Fellowship of the Ring" to decide the fate of the One Ring, an all powerful ring which is being searched for by the evil Dark Lord Sauron. (It's ultimately decided they need to destroy it.)

It's not a subtle reference in "The Martian."

The actors go on to reveal for unsuspecting audience members the name is a nod to "The Lord of the Rings" council.

Here's how the scene plays out in the book by Andy Weir:

"What the f--- is 'Project Elrond'?" Annie asked.

"I had to make something up," Venkat said.

"So you came up with 'Elrond'?" Annie pressed.

"Because it's a secret meeting?" Mitch guessed. "The email said I couldn't even tell my assistant."

"I'll explain everything once Teddy arrives." Venkat said.

"Why does 'Elrond' mean 'secret meeting'?" Annie asked.

"Are we going to make a momentous decision?" Bruce Ng asked.

"Exactly," Venkat said.

"How did you know that?" Annie asked, getting annoyed.

"Elrond," Bruce said. "The Council of Elrond. From Lord of the Rings. It's the meeting where they decide to destroy the One Ring."

However, the joke didn't end there for LOTR fans.

The best part is that actor Sean Bean is sitting in on the scene as Mitch.

Why does that matter?

Bean played Boromir in "The Lord of the Rings," and was a part of the Council of Elrond.

Bean may have been making this exact same motion in "The Martian," too. Warner Bros./New Line Cinema

It's a fun extra nod to the series.

Here's Bean during the "Project Elrond" scene.

20th Century Fox

"The Martian" is in theaters now.