Why do I see a colored grid/registration artifact in a Hasselblad H4D-50MS image?

That is the result of using the H4D-50MS in multishot mode with an uncontrolled subject. Notice that everything that is absolutely still comes out just fine, but anything that moves, even slightly, shows registration problems. The vehicle is most obvious since it's moving at a decent clip, but the motion is also visible in the water, grass, and so forth.

In multishot mode, the camera takes four pictures (at about a second or so apart), moving the sensor by one pixel left/right/up/down between shots. That's a wonderful thing for studio still life—it means that every pixel of the resulting image was imaged by each of the four pixels in a Bayer quad, so each of the pixels has its own complete colour coverage (and doesn't have to rely on inference from surrounding pixels for colour info). If the subject moves at all—and keep in mind that the sensitivity is a single pixel in any direction—at least the colour information will be wrong, and you may get extreme ghosting (as with the SUV).

The solution is to ensure that mulishot mode is only used for controlled still life set-ups. (Or, perhaps, for extremely stable landscapes, like rock formations or deserts in still air and clear skies.) If there's any possibility of something moving, there will be artifacts in the multishot image, often more than can easily be fixed in post.