According to our current understanding of physics, nothing can travel faster than the speed of light in a vacuum. This speed is considered the universal speed limit. If there were a flash or any other object that could emit or move faster than light, it would violate the fundamental principles of special relativity.
In the context of your question, if such a flash were to occur and move faster than light, it would defy our current understanding of the laws of physics. The flash would be considered to have exceeded the speed of light and, therefore, travel outside the light cone, which represents the boundary of causally connected events.
However, it's important to note that there is no experimental evidence or scientific theory supporting the existence of objects or phenomena that can move faster than light. As a result, the scenario you described is purely hypothetical and not consistent with our current understanding of the universe.