A shadow can race across a distant wall faster than light, yet nothing in that scene violates relativity. The key is that the shadow is not a physical object made of particles. It is simply the absence of photons in a pattern defined by a blocking object and a light source.
In special relativity, the speed limit applies to signals and matter that carry energy and information. Photons move at light speed, and no material object can outrun them in vacuum. A sweeping flashlight beam sends out new photons in slightly different directions, but each photon still obeys the same limit. The moving dark patch on the wall is a geometric effect, not a traveling thing. No atom, photon, or data packet slides sideways along the wall at that superluminal rate.
This is similar to the way a laser dot can skid across the surface of the Moon faster than light if the laser is pivoted quickly enough. The apparent motion is just a changing intersection point of straight light rays with a surface. Because no localized disturbance moves continuously from point A to point B, no information can be encoded in that faster than light motion, and causality in spacetime remains intact.
