If a sealed elevator were subjected to a massive acceleration in interstellar space and two weights were dropped from ceiling to floor, as far apart as possible on opposite sides of the elevator, their paths from ceiling to floor would be parallel. But supposing this hypothetical, thought experiment lift were resting on the surface of a planet-like body where it is subjected to an identical g force, would the paths of the falling weights still be parallel?
No, they would not still be parallel.
This is because a planet-like body has a curved surface, and the acceleration due to gravity will point towards the centre of the (approximate) sphere. This means that at each different point on the surface of the sphere, the acceleration is pointing in different directions, and cannot be parallel.
For a planet the size of Earth, the diameter is very large, so the direction of gravity between two close points is approximately parallel, and it may not be possible to measure the angular difference between the two paths unless they are spaced significantly far away. This would obviously depend on how you are measuring the paths.