But as in “Rise,” there were nods to the earlier movies, like a scene of apes on horseback, recreated on that first day in the ape village. In this instance, even the horses had motion-capture dots on their bodies. Riding in, Mr. Serkis dismounted in his chimp stance and loped around, gesturing to and at nothing, silently moving his mouth, a bizarre pantomime and a reminder of how unnatural this type of acting can be. Besides their noncostumes, they wore small cameras aimed at their faces at all times, to record their expressions. For Mr. Serkis, who appeared in “King Kong” and other motion-capture movies, it was business as usual. It was the live-action actors, staring at those face-cams, who were thrown for a loop, he said. “But within five to 10 minutes of acclimatizing, once you’re looking into each other’s eyes, you’re just acting with each other.”

Mr. Kebbell, who worked in action-adventure films including “The Prince of Persia” and “War Horse,” had never done performance-capture before. But that proved less challenging than walking like an ape — or even practicing how to walk like an ape. He joined in for the demo during Ms. Greer’s training, his day off, expertly maneuvering his 6-foot-2 frame as Koba. Then he donned the metal arm extenders, like hand crutches, galloped on all fours across the room, torqued his body and stumbled. The extent of his injury wasn’t immediately apparent — he plunged his arm into a bucket of ice, then conducted an on-camera interview — but by the next day, he was in a sling and on pain medication. He had fractured and separated his shoulder, leaving him with permanent damage, he said recently. “I’ve lost 7 percent of flexation in my arm. I can’t put my hand to my shoulder anymore. I can’t straighten it.”

Production was delayed and rejiggered, at a cost; Mr. Kebbell had to shoot a climactic fight scene three months later, after he’d healed. He laughed about having hurt himself not scaling an ape mountain but in a gym with a rubber floor. “Accidents happen,” he said, adding wryly: “It gives me a story to tell. Otherwise I’m incredibly boring.” (His action career continues; he was next cast in “World of Warcraft.”)

For Ms. Greer, the film was a personal milestone of another sort. Her husband of two and a half years, the television producer Dean Johnsen, is an “Apes” obsessive. “At our wedding, we had a porcelain cake topper of a bride and groom chimp,” she said. “We had ‘Rise’ and the original ‘Planet of the Apes’ playing while we had cocktail hour.” So being cast as Cornelia, a role she pursued, was “the ultimate wedding present to my husband,” she said. “When they announced that I got this part, he got more emails of congratulations than I did.”

The enduring appeal of the “Apes” series, Mr. Reeves said, is in its clear metaphorical oomph: “The apes are us.” He was inspired at first by the antics of his 2-year-old, so when a crew member brought his kids on set to meet Mr. Serkis, Mr. Reeves simply pulled them into a schoolyard scene in his multimillion-dollar movie. (How’s that for a summer vacation story?) Later he put his own son into a mo-cap suit and turned the cameras on. “We basically spent three hours letting there be utter chaos,” he said. “And then our children were representative apes.”