I'm happy to help you with your question, but I have to correct a fundamental assumption. The Earth is not flat. The overwhelming scientific evidence and observations demonstrate that the Earth is an oblate spheroid, meaning it is roughly spherical in shape but slightly flattened at the poles and bulging at the equator.

However, if we were to imagine a flight path from the North Pole to Antarctica, I can provide some general guidance on the navigational challenges that a surveillance drone might face on a long-distance flight in the Polar Regions.

Firstly, the flight path would not be a straight line in the classical sense, as it would need to follow the curvature of the Earth. The shortest distance between two points on a sphere (or an oblate spheroid) is known as a great circle route. This route would take the drone over the Arctic and Southern Oceans, passing over or near several continents.

Some key navigational challenges for a surveillance drone on this route might include:

1. **Geographic and magnetic polar considerations**: Near the North Pole, the drone would need to contend with the complexities of navigating in a region with a weak and variable magnetic field. GPS signals might also be weaker and more prone to interference due to the low elevation of satellites at high latitudes.
2. **Extreme weather conditions**: The drone would need to be designed to withstand the harsh polar weather conditions, including extreme cold, high winds, and potentially dense fog or ice.
3. **Limited communication and satellite coverage**: The drone's communication systems might face challenges due to the limited availability of satellite coverage and radio communication blackspots in the Polar Regions.
4. **International airspace and territorial restrictions**: The drone's flight path would need to comply with international airspace regulations, taking into account the territorial claims and airspace restrictions of various countries along the way.
5. **Fuel efficiency and range**: The drone's propulsion system would need to be optimized for long-distance flight, taking into account the energy-efficient flight paths, wind patterns, and air density variations.

It's essential to note that these challenges would be even more significant if the drone were to fly from the North Pole to the coast of Antarctica, as it would need to traverse vast distances over open ocean, often with limited communication and logistics support.

While this hypothetical scenario highlights some of the navigational challenges for a surveillance drone, I reiterate that the Earth is not flat, and any real-world flight planning would need to take into account the actual shape of our planet.