Apparently it was finished under director James C. McKay and shown to preview audiences; the little kids freaked out in particular at a scene in which vampire bats carried off natives, and it was significantly, or wholly reshot by Richard Thorpe and John Farrow (who met and married Maureen O'Sullivan as a result of working on the film). Opinion seems to differ on how much it was reshot, and the film does show signs of rather blunt editing (ie, what follows where the bat attack would be seems like it's the remnants of the original scene), but there are other aspects of it that indicate wholesale reshooting. In the original version Jane's cousin Rita (Benita Hume) puts the moves on Tarzan; there's none of that in the final version, in which she's sort of a bland goodie two-shoes. And if, as one source says, the treehouse set with all the modern, Flintstonian conveniences like an elephant-powered elevator was an addition, then that means the entire middle of the picture, which is set there, has to have been reshot. Likewise, if Herbert Mundin's character— who is comic relief but also a bit heroic by his end, and somewhat steals the movie— was an addition, that too means that most of the first 2/3 of the movie must be new.
The big difference, I think, is that MGM's attempt to use Tarzan as a way to push the production code came to an abrupt end here, and the result pushed the Tarzan series into the kiddie film category for the rest of its run. The Tarzan craze seems to have run its course at last, but for most of the 20th century, as more and more young men went to work for regimented corporations, this myth of a barely clothed natural man behaving freely in the jungle, including with his common-law wife, was one of the most potent in our culture, and Edgar Rice Burroughs was at one time the bestselling author in the world. So the first two Tarzan movies, with their attractive stars cavorting nearly in the nude, were made for adults, not kids. But Tarzan Escapes, in its final version, pushes it definitively into the kid category, not only because Jane's love for Weissmuller's monosyllabic simpleton act doesn't really make emotional sense for adults (seriously, he hasn't learned any more English by now?) but because Tarzan is, in this movie, genuinely domesticated in his gimmicky-filled split-level mansion up in the trees. My kids enjoyed it just fine, but Dad spent the movie papering over the holes in the concept, and it would be at least 20 more years, if that, before a credibly adult and on some level savage Tarzan would be seen again on the screen.

An ad still featuring the excised vampire bats.