Using a drone, we can observe a sunset, then climb up and watch the same sunset again for the second time. The observation is only possible because Earth is a sphere.
Flying a Drone Inside a Moving Vehicle
If we fly a drone inside a vehicle that is moving in a constant speed and direction, the drone will hover normally because it preserves the motion it gets from the vehicle. It will not abruptly move toward the rear of the vehicle.
Flat-Earthers claim that it should not be possible for drones to hover if Earth is rotating. In reality, drones follow Newton’s first law of motion and will preserve their inertia. It is easy to demonstrate the phenomenon by flying a drone inside a moving vehicle. The fact that drones can hover still in mid-air is not evidence of stationary Earth.
Climbing Higher Reveals Distant Objects
Because the Earth is a sphere, the surface of Earth obstructs distant enough objects. Climbing to a higher altitude allows us to see farther and more of the previously obstructed objects will become visible, starting from the tops first.
This phenomenon would not occur if the Earth were flat. In a flat Earth, it would not be possible for Earth’s surface to obstruct more of an object —starting from the bottom portions first— if the observer is closer to the surface.
The same thing also happens for objects nearby a large body of water. The surface of the water —which is obviously lower than the object— can obscure the object if the viewer is far enough. Flat-Earthers often invent the “explanation” that Earth’s contour causes the obstruction. This phenomenon can easily prove them wrong.