According to Nimród Antal and Robert Rodriguez on the commentary, in the script, the character Cuchillo was described as "a guy who looks like Danny Trejo." When Danny Trejo heard this, he called Robert Rodriguez and said, "hey, I heard there's a guy in the script for 'Predators' who looks just like Danny Trejo, and guess what, I look just like Danny Trejo!"
Hanzo is missing two fingers on his left hand. The reason that the Yakuza traditionally cut their fingers starting from the left pinkie, is that these fingers have a vital role in controlling a Japanese sword, and their loss would significantly impair a duelist. Hanzo must be a formidable swordsman to be able fight in close combat as he did, despite the loss of his fingers.
The plant that Edwin (Topher Grace) identifies as "Archaefructus liaoningensis" has actually been extinct for several million years; its origin lies in the Cretaceous Period. Angiosperm fossils were found in China, that are believed to be about one hundred twenty-five million years old, making it the world's earliest known flowering plant. In an earlier draft of the script, Edwin highlights the plant's origins, citing it as yet another inexplicable oddity, before they finally realize where they are.
The original script contained cameo appearances by Dutch (Arnold Schwarzenegger) and Michael Harrigan (Danny Glover), the protagonists of the previous Predator films. However, these appearances were ultimately cut out.
According to Robert Rodriguez on the DVD commentary, Walton Goggins had been cast in the role of Stans, but Rodriguez felt the character was written far too much like the character Hudson in Aliens (1986). So Rodriguez had the part re-written, and asked Director Nimród Antal to re-cast the role. But Antal insisted that Goggins could still do the role, and scheduled a meeting between Goggins, Rodriguez, and him. Within a very short period of time, Rodriguez was convinced that Walton was right for the part.
The pool with the overhanging rock, where the group ends up after the jump from the cliff, was found in Texas, during location scouting. However, when the scene was shot a few months later, the temperature had dropped considerably, and water had started to flow from the rock. Not only did the actors have to be submerged in freezing cold water, the noise from the waterfall made the recording of usable dialogue impossible.
Nimród Antal specifically chose Adrien Brody for the main protagonist: "It was a challenge in finding a balance. When we cast Adrien, there were a lot of people going, What? But at the same time, if we cast a Vin Diesel in that role or anyone who is Arnold-esque, we would have been attacked for doing that. So we decided early on to go in a very different direction as far as the casting process, but it turned out fantastic." He also felt the soldiers should be portrayed as wiry tough guys, not burly men, like Arnold Schwarzenegger.
The song that plays over the credits is Little Richard's "Long Tall Sally", which was listened to by the main characters of Predator (1987) on the helicopter before they're dropped into the jungle for their mission.
According to Robert Rodriguez, the title of "Predators" serves as a double-entendre, describing the alien hunters as well as the ensemble human characters they target: "They could very well kill each other off, even if there were no Predators!"
The film's basic plot was conceived in 1994, when Robert Rodriguez was working on Desperado (1995). He presented a draft of the script to 20th Century Fox, but they turned it down, because the budget required was too large. Fifteen years later, the studio decided to follow through with his script; in the end, an updated version of his script.
Royce, Isabelle, Nikolai, and Noland are the only people to say their names in the film. Stans, Mombasa, Cuchillo, Edwin, and Hanzo's names are never revealed (although Stans identifies himself in a deleted scene). The DVD captions identify all characters.
The man whose parachute fails to open is wearing pixel-gray Army Combat Uniform fatigues, meaning he was most likely a soldier in the United States Army. The same goes for the unidentified man found later with his chest ripped open: Nikolai reads from the man's notebook that he was supposed to be stationed in Afghanistan.
(At around fifty minutes) The Insectoid Alien that appears is an allusion to the original design of the Predator from the first film, when it was played by Jean-Claude Van Damme. The creature was redesigned after Van Damme's departure, to the current design.
Isabelle uses a Blaser R93 sniper rifle, fitted with an Elcan DigitalHunter scope. The official sniper rifle for active-duty Israeli Defense Forces personnel, is actually the H-S Precision HTR, and it achieved that designation in May 2010, only a month before this movie was released.
Nikolai was originally supposed to be armed with a Russian GShG-7.62 four-barreled rotary machine gun, as it would be more fitting for a Russian Spetsnaz Operator. The production crew was unable to obtain one, so they used an American M134 minigun instead.
At the point Noland (Lawrence Fishburne) is introduced, you hear the lines "Over Here" and "Turn Around". These lines are spoken by Bill Duke to Carl Weathers in the first Predator movie. The lines are either a nod to the original movie, or represent the Predator's ability to record and transfer sounds and data between themselves in real time, as the first Predator didn't survive, to do this himself.
In Decloaking the Invisible: Alien Terrain (2010), it can plainly be seen that stunt performers were used for the cliff fall scene, in most of the shots, if not all of them, that were actually used in the movie. This is especially true for Edwin's fall. This was done by a professional, and he still accidentally landed mostly on his head.
One indication that the Predators have been using the hunting grounds for a very long time, is when they first come into the Predator camp (just before they see the classic Predator on the totem pole), there is a Neanderthal skull next to a human skull on the ground as a trophy. The Neanderthal subspecies became extinct forty thousand years ago.
Stans is a death row inmate in California's San Quentin Correctional Facility. All death row inmates can receive a pardon, or stay of execution by the state's Governor. At the time this film was made (and presumably the time the movie takes place), California's Governor was Arnold Schwarzenegger, the star of Predator (1987).
The original, rejected script had the Predators riding motorbikes and drinking alien beer while watching matches in a Coliseum-like arena. Furthermore, there would originally have been 200 Predators in the movie. Nimród Antal, a big fan of the franchise, found these ideas preposterous and had them changed. He reasoned that a single Predator posed a dangerous threat in the previous films, so it would be unreasonable for any of the human characters to survive dealing with hundreds of them. Basic ideas that were kept throughout included the story taking place on an alien world and six out of the eight human characters getting killed.
The film stars two Academy Award winners and one nominee: Adrien Brody won Best Actor for The Pianist (2002), Mahershala Ali won Best Actor in a Supporting Role for Moonlight (2016), and Laurence Fishburne was nominated for Best Actor for What's Love Got To Do With It (1993).
Shortly after being hired as the director, Nimród Antal was informed that the movie will be scrapped because the script wasn't deemed good enough. Antal was then given two screenwriters and ten days to write a new story outline from scratch in their basement. According to Antal, by the end the place was such a mess and smelled so bad that the Predators' camp in the movie was heaven in comparison.
Even though this installment in the "Predator" franchise explicitly wanted to part with the crossover AVP story arc, it does contain at least three nods to the Alien franchise: - 1) at one point, while (obviously, given the movie's universe) facing near-certain death, one character tells another "If the time comes, I'll do us both", a reference to Hicks' almost identical line in Aliens (1986), 2) when the group finds the body of an earlier victim of the antagonists, he has a large hole in his chest with the ribs bent outwards (probably from a Predator energy blast shot from behind), referencing the way Xenomorph young emerge from their host, and the wound found on the "space jockey" in Alien (1979), also Nikolai references Billy's dialogue from Predator (1987), "he set up position here, he was shooting in all directions" 3) as soon as Royce recovers from his parachute landing; as he looks around, a music motif from Aliens (1986) can be heard, and when the group enters the Predators camp, there's a brief view of an Alien skull on the ground. Additionally, when realizing that the Classic Predators may be helpful against the Super Predators, Royce mentions 'my enemy's enemy', which references the 'enemy of the enemy is my friend' concept from AVP: Alien vs. Predator (2004).
When Hanzo sees the ancient Samurai katana in the ship, and realizes it's very old, he removes it from the sheath. This is anathema to bushido (Samurai code) as it cannot be put back into its sheath, unless it sheds blood. Hanzo would have let the blade cut his thumb to keep the "soul" of the blade strong.