The obvious: Mermen don’t have pant puppets.
To figure out why I had an “Oh crap,” moment when I saw Kismet in her bio hit my Kismet tag. The movie review appears to say, “oh crap”, too. This comes from “Florida Memory” and the state archives. “Ed and Whitey McMahan carry actress Ann Blyth to the underwater set during filming of Mr. Peabody and the Mermaid at Weeki Wachee Spring.”