A search on the internet fails to turn up anything at all on this film (aside from one mention on another Board, cited above, which for all I know might have been made by kitemaker under another name) .
I was prepared to completely write this off, but then I remembered something from my youth. On the Sunday morning WNEW Channel 5 kids’ show Wonderama they used to show a lot of odd short films, and there was a series, IIRC, that had all-chimpanzee casts. It’s conceivable that one of these was a mock Western called “The little Covered wagon”. A lot of those old time-filing theatrical shorts and TV fodder (which is what I['m sure this must have been) haven’t been well-catalogued, and might not yet show up on any internet sites.
If that’s what this was, then it’s not a full-length film by any means, but a 5 minute or so short, probably with a cheap joke at the end.