timdiggerm said:
(Never mind that the inside of the slug is a vertical shaft and they’re walking on the side of it)

You could say that due to the sheer size of the slug that where they landed inside it essentially oriented them straight down or near enough with the centre of the asteroid and so it would be no different than if they were standing on the surface if you drew a line straight upwards from their head. The asteroid could also have a much denser core, attributing for the level of gravity due to their closer proximity inside the slug.

There’s nothing in the movie to indicate any of this though so its pretty much just a standard old plot hole 😉