When Ron said in his review - "Blatant pop-out gimmickry is pretty much non-existent here. There is an attempt late in the film to throw a lantern towards the audience, but it never lunges itself outwards. However, interestingly, the brim of Robert Ryan's hat does seem to poke itself outside of the screen on one or two occasions." I was thinking this film is mostly about depth. There were a number of scenes with Robert Ryan looking down the mountain that do have a lot of depth but, there are a number of scenes where actors are near the front of the screen and their entire body is out of the screen. For an example:
At 09:50 Rhonda Fleming and William Lundigan are both out of the screen.
At 09:55 William moves backward and just Rhonda is out of the screen.
At 10:00 William moves forward, they are both out-of-the-screen.
Very impressive 3D.
Of course I'm watching this from my Panasonic AE8000 projector, producing an image 70 by 93 inches, sitting about 15 feet from the screen.