The gaps appear to be different sizes.
They had to build various sets that looked like they were on board the ship throughout the filming of the movie. However, this raises the question of how many replicas of the ship there were. The rails in one shot resemble those in the photo above. In another image, the distance between the rails narrows and takes on a whole other appearance. This may not be obvious to spectators, but it should have been spotted during editing.
