in film-making, this practice would be called "crossing the line" and was something they were taught to avoid doing randomly.
Yes, that or the "180-degree rule"; however it's an advisement, and not an actual law, so it can (and is) broken from time-to-time!
Actually, the point I was making (or trying to make) is that it's only by comparison with the original that the reader would know the Captain has "turned round". Without that information, he doesn't.
Just going by what we see, the land is on his right, by inference the sea is to his left over Hergé's shoulder, and therefore he is heading in the same direction he always was, up the beach away from Thompson and Thomson. Without the additional frames showing him face-to-face with the Detectives, that's really all we can tell, and therefore, apart from a bit of iffy "cinematography" the story runs "correctly".
It's worth bearing in mind, I think, that the direction of travel across the frame had meaning to Hergé, who saw movement left-to-right as narrative progress, and achievement by his characters, and right-to-left as representing set-back and upset (I've read this, but to be honest I've not stopped to check how heavily he applied it).
This could mean that, for story-telling purposes, the line was crossed on other occasions. It's entirely possible that the 180-degree rule was less important to him than to film makers.
being under pressure and pushed for time wouldn't have been unusual at this point in Hergé's career.
That's absolutely true, but while the week-to-week churning out of the double-page full-colour strip for the magazine must have been a grind, it might have been thought that there was a little less pressure on him when the album was to be prepared, especially when by this point his colleagues were well-used to the draw and re-draw process Hergé favoured. With assistants like Jacobs skilled in supplying new backgrounds for Hergé's character figures, taking the tiny shreds of sea out and inserting the mountain-scape in the back would seem remarkably trivial.
presumeably knowing that all the frames would then have to be re-jigged down the line to fit the book format.
I'd need to look it up, but I've a feeling it was a slightly more mechanical process than one might think, and was prepared for.
I'm maybe way off beam here, but I think
there was a bit of preparation built in, with the framing on the landscape pages done to allow the re-jigging of them into the album version with less work, so that you'd get a frame break when the end of an album "row" was reached, or some frames were drawn as "padding", with the intention of dropping them for the book. It wasn't infallible, but I think it helped.
I could be entirely wrong, as I can't remember where I saw that stated (perhaps it was at the Inca exhibition in Brussels?)
(I really should get the magazine version! Is it still in print?)
It's certainly available again, as part of the two-volume La Malédiction de Rascar Capac
set, which collects the black-and-white Crystal Balls
in volume one, and the Journal
version of Prisoners in volume two. Not seen them myself yet, but it's meant to be a good collection, edited by Philippe Goddin.