Yeah, that couple of branches moving slightly actually looks unintentional because it happens so far away (ie it doesn't seem like it's supposed to be noticed otherwise it would have been more foregrounded,) and also I know that Guinness was in poor health at that time so I assumed they couldn't retake the shot.
But Yoda is also sitting on the railing in the Ewok village ending. To me these things are no more than the fact that "regular" ghosts are generally presented as walking on floors even though it really makes no sense for them to "obey the laws of the physical world." So the OT force ghosts are not much more than what we expect of regular ghosts.
I think what's being discussed above is as if a regular ghost was able to do something with apparent superpowers (like to move extremely heavy objects or destroy something with massive energy blast,) which is different to simply conforming to the laws of the physical world.
I'm sure that was unintentional.
Of course, i am sure it could be argued either way(And for the record, i am not trying to argue this point. Only pointing it out).
We all of us here know the reason Obi Wan brushes the tree branches aside is that:
1: He wasn't actually a ghost. He was an actor on a real set, in frail health, and unable to avoid pushing past the branches,
2: The movie special effects industry(While, at an all time high with ILM in the mix), were probably not up to the task of editing out the moving branches,
So, as ZE_501 says, it's not "on purpose".
But. It's there all the same. So we could each have our own point of view on where it was "Always a thing", or "Has just become a thing"(All down to personal preference). People who like TLJ, and TROS, will see it as further proof of their interpretation, and people who hate the ST, will be able to ignore it as an unintentional flub.
And while i wouldn't say it proves anything definitively(And, like i say, i am merely pointing it out, not taking on stance or another on force ghosts being able to affect the real world), we saw Yoda call down lightning on a tree, and Luke Lift up an X-wing. So it's a thing in the movies, even if a few(Or many) members here don't like the inclusion of new force powers we haven't seen before.
I fall into the camp of "Don't really mind seeing new powers, even far-reaching ones". While it's easy to say: "If it was do-able before, the Jedi would have discovered it", but that could also be said of becoming one with the force. It wasn't a thing till it became a thing.
Back in the day, we all thought that force choking was something only the baddies could do(Because in ANH, while we see Obi-Wan using a mind trick, and sensing the destruction of alderaan, but not using any other force powers, like Vader does), and then in TESB, we see it's an inherent force power and Luke and Yoda use it. The same with the acrobatic stuff Luke does in TESB when he's training(And jumping out of the Carbonite Chamber). Till then, we hadn't seen that done. And the way it's done in TPM, AOTC and ROTS, just shows how great and powerful the Jedi must have been at the height of their power.
Like any other force power, it's all made up anyway.
Can you believe it? If you can, the movies are enjoyable because of some space wizard magic. If it strains your disbelief in a movie where live people can lift spacecraft with their minds, but the faintly represented dead people doing the same takes you out of it... That's your choice. But if you can just "go with it", you'll enjoy it a lot more, lol.
