(I'd comment on your clip, but I can't download it at the moment - firewall)
As Luke goes deeper into the cave, we can see that there is a stone arch there, like this is an old abandoned temple or something. There's probably some EU explanation for this, but for just a movie purist, it's a little confusing. Would you consider doing something about the arch?
Maybe remove it so that it looks like a natural cave?
Or maybe use the arch element to create a wider shot that shows us a hall with lots of arches? (kind of like the wider angle you gave us when Luke and Leia swing across the chasm)
The second option wouldn't really solve the confusion issue, but it would at least make it look like this is an "intentional mystery" and not some random set piece that got reused because they were cheap.