IN ACTING CLASS it’s called space work, a sort of pantomime to create the illusion of handling an object that isn’t there, like smoking an invisible cigarette. Keanu Reeves resorts to space work when he describes his new motorcycle, putting his fists out and sitting on a low-slung imaginary saddle while leaning hard into the Malibu Canyon hairpin that never seems far from his mind.

“It’s a bike that when you get it down in the corner, you can just—Huh!”—he swivels his hips, blips the throttle, squints his eyes, bites his...