Factual error: There are just a couple of things wrong about the gas grenades used in the movie: gas grenades do not explode, they spray their contents; and second: if the gas really is that powerful, it should be used with more caution; a simple sudden downwind breeze into an uncontrollable gas cloud, and the users would become their own victims.
Factual error: A creature of Kong's size would not be taken out that easily with the gas grenade as in the movie, for: 1) it explodes far too low for the gas to affect him; 2) even if the gas had reached his breathing organs, it would have taken more and prolonged exposure to knock him out.
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 ★