Other mistake: While Ann Darrow is lying on the Empire State Building ledge beside the ladder, the backdrop shows the Chrysler Building, Queensboro Bridge, and Roosevelt Island, behind to the right. However, after Kong falls from the skyscraper, when Jack appears and says, "Ann, hang on, dear," this one shot is angled toward the left of the ESB, but the set's backdrop is positioned so it's the same background with the Chrysler Building, Queensboro Bridge, and Roosevelt Island, behind to the left. (01:38:20)
Other mistake: When the planes attack Kong, for a brief moment the superimposed footage of the staircase below jumps to the left. (01:32:47)
Answer: It's never shown or explained, and the film uses a broad "suspension of disbelief" premise. The audience just accepts the characters were able to somehow transport a huge ape to New York City.
raywest ★