Some of the main things in quantum mechanics that are head scratchers is quantum entanglement, zero point energy, Casimir effect, quantum tunneling, superposition, etc.
I met someone once whose last name was Casimir, I refrained from asking her if she was familiar with her namesake, the Casimir effect.
You can't travel faster than the speed of light, but the universe overall is expanding and there are are galaxies so far away that the space between them is expanding faster than you can actually go there even at the speed of light due to dark energy. Basically you bake a loaf of bread and the two ends of the loaf expand away from each other and the distance becomes so great at some point that you can never reach the other end even at the speed of light.