I have always wondered what really happened to the Jurassic Park gate prop, and the "stone" archway. Does Universal Studios have the "stone" archway for their Jurassic Park ride?
His recollection is that he is quite sure that the gate was ...
"...struck and trashed after the filming..."
...and that whatever remained of the gates and materials were obliterated by the elements, notably ...
"...hurricane Iniki [which made landfall] during the end of the production on the island of Kauai, Hawaii, which probably damaged them significantly."
It's possible that pieces of the gate could be found nearby the gate site (noting that the poles that are show to tourists aren't actually part of the original since they're nearly a hundred feet ahead of the site where the gate was placed) if one were to look hard enough, but since the gate was likely made out of little more than flimsy sheets of balsawood painted brown for wood and grey for stone, they could literally have gone anywhere.
There are several YouTube videos of people going to the location of the Gate filmed in the movie.
The actually Gate was located about 300 feet past these 2 poles. There is nothing left of the gate.
The last 2 give a pretty good description of how to get there if you want to see it yourself.