Lots of filmmakers have their calling cards. Hitchcock liked to cast himself in small cameo roles. John Woo likes doves. Penny Marshall kept giving work to Jon Lovitz (not all calling cards are created equal).
For Stanley Kubrick, one onscreen signature involved the use of one-point perspective, in which a single distant point, often dead-center in the image, is used as a spatial reference. This leads to a very symmetrical viewpoint, as the outer edges of the picture all gravitate toward the center. Very cold, occasionally unsettling. Oh so Kubrick.
Here's a supercut of all the scenes from Kubrick movies that employed this visual device. As is often the case, it's easier to explain visually than in words:
See what I mean?