When a chimpanzee and an orangutan wander by on a dark night, you stop to notice.
But for the cast and crew of War for the Planet of the Apes, it was just another day at the office, which in this case was the massive Canadian set of the third installment of the series.
Twentieth Century Fox rolled out its newest trailer for the film, set for release this summer, to theatre owners and media at CinemaCon in Las Vegas this week.
But that slick, computer-generated preview is a far cry from December 2015 when West Coast rain turned an already oppressive prison camp set built in Richmond, B.C., into a muddy canyon of iron.
Producers invited a small group of media to tour the set, bundled in boots and waterproof layers.
The sprawling compound was littered with cages, guard towers and military huts. The only bright glow surrounding it came from the massive green screen fence as smoke machines cranked nearby.
Actor Andy Serkis spent much of his time there encased in a motion-capture suit which, through the magic of computer animation, transformed him into the film's brooding protagonist Caesar the chimpanzee.
"Apes are humanoid characters ... in essence, the same shape as [humans]," said Serkis, wearing a motion-capture helmet and camera, his face dotted with sensors to catch every muscle twitch and expression.
"But when you're really starting to move away from that into the more abstract, that's really becoming very interesting and exciting, so yeah, when I see those things coming to life, it's incredibly thrilling."
Darting alongside Serkis is Terry Notary, reprising his role as Caesar's follower, Rocket.
"You don't play an ape," said Notary, an accomplished stunt coordinator and movement coach. "You just drop into a deeper sense of yourself, and that's when an ape comes out ... when it works."
How to become an orangutan
For actor Karin Konoval the challenge of playing an animal hundreds of pounds heavier than herself is one she conquered through sheer will and pain.
"In terms of being an actor, it's the same job in performance capture, as it is in any other role as an actor wearing normal clothes. It's just a heck of a lot harder," said Konoval, who brings Maurice the orangutan to life on screen.
"What's harder about it is playing a character of another species, that's the thing."
Shortly after chatting with reporters, Konoval loped by wearing her metal arm stilts, the props used to create Maurice's incredibly long, powerful limbs.
No easy task in a mud-covered prison set meant to hold apes in.
The apes are set to be released July 14th.