“If you are traveling at the speed of light and turn your headlights on, would they still work?” - Steven Wright
That’s a good one. I think the answer is that you would see the light shining out at the speed of light in front of you. It’s the relativity thing.
What was a neat thing to learn, also, is why, say, a planet cannot travel at light speed. As it rolls along, the increased speed gives the planet more momentum. Momentum is kinetic energy. And by e=mc2, the kinetic energy is equivalent to increased mass, making acceleration require even more energy. Or something.