One does have to ask though, why then isn’t this 180 rule taken into consideration much more when actually filming the scenes? Is this not part of the directors job?
It 100% is but everyone makes mistakes. The majority of the time they factor it in and it works fine. Sometimes one shot of a scene could be done days or weeks before the next (not often, but possible on an effects picture like this) and it’s easy to slip up. Sometimes they did two shots that they didn’t necessarily envision cutting together (maybe there was supposed to be a cutaway but that’s gone and now its jarring). And of course, any rule is just a guideline, so maybe they knew they were breaking 180 but thought it would work okay, but ultimately it didn’t.