... and why am i thinking about FROGS..!??
Not too sure... but that top pic of yours is giving me strong urges to get to the other side of a busy road.

... and why am i thinking about FROGS..!??
As for inconsistencies in studio models....its more common than we realize. Often they have different teams making different scales of the same thing, or they're so danged pressed for time they can't make it a perfect match...plus they probably had unit directors and producers saying "Who cares, its close enough...get it done, we need to shoot it tomorrow."
The Rodger Young, the Serenity, the Millenium Falcon, you name it, just about every studio model that's been made more than once in different scales has its share of inconsistencies that drive us modellers nuts. Just so long as we remember that WE who are the ones with the "issues" not the folks who made 'em in the first place.
Just an interesting little tidbit of trivia to add. In the novelization by Alan Dean Foster of O'Bannon and Shusett's screenplay, the Nostromo's registry number is 180246 (see page 22 of the paperback by Warner Books published in 1979). It also described the refinery as being an oil refinery, bringing a load of soon-to-be-refined petrochemicals back to Earth.