The main building may have been destroyed in the production, as the house burns to the ground later in the movie. The above shot has the survivors burying two poor souls killed in an attack on the farm, and the charred remains of the house can be seen in the background, behind the rider on the right. It seems unlikely that they would have gone to the lengths of actually destroying a building to get the shot, but who knows? This shot seems to support the theory that the house was just a front and was perhaps designed to ultimately be destroyed on camera. Either way, at least part of the set — the shack, partially visible at the left of both of the above shots — survived and went on to appear in a number of productions, including episodes of the "Lone Ranger" TV show.
Here's "Platypus Shack" again, along with the rock Platypus, in the "Lone Ranger" episode "Barnaby Boggs, Esquire," which premiered Feb. 2, 1950, during the TV show's first season. The shot ran properly oriented in this episode, but in a different episode, the exact same footage was used — but flipped horizontally, as seen below:
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One more "Lone Ranger" shot, back to the "Barnaby Boggs, Esquire" episode, where Platypus Shack ran in its correct orientation. This shot offers a better look at the shack, with the Lone Ranger, played by Clayton Moore, circling around back. The shack stood from about 1949-1952 and appeared in a number of movies, including the Whip Wilson B-Westerns "Gunslingers" and "Silver Raiders" for Monogram (both 1950) and the Rocky Lane B-Western "Marshal of Cedar Rock" for Republic (released in early 1953 but filmed in 1952).
Here's another look at Platypus — the rock, minus the shack — in the slightly upscale Columbia B-Western "The Gun That Won the West" (1955).
And here's a real Platypus. Maybe you can see the resemblance in the bill, which gives the rock its name. I'll take the blame for it.
The 1957 George Montgomery Western "Gun Duel in Durango" provided this unusual shot of Platypus' neighbor to the east, Fish Head, with a couple of sentries on it — including one sitting on its fish lips. As a footnote about Platypus and Fish Head, I believe both of these distinctive and heavily filmed rocks have survived, although I've never seen them in person. If they do still exist, they're "living" in someone's back yard on the former Upper Iverson Movie Ranch.