When Godzilla leaves the Roman Colosseum, he knocks down and destroys a large section of its outer walls. When Godzilla returns to the Colosseum later, its walls are intact again.
In the trailer, one of the camel riders around the area where Kong is coming from beneath the ground, begins to run away from the site of Kong's emergence. Shortly thereafter, as it appears it is about to fall into the hole created the camel actually gradually fades out of existence over a couple of seconds. This can be observed in both the trailer, and the final cut of the film available in theaters.
When arriving at the outpost in hollow earth is clearly hinted that a bigger ape (Skar King) did the destruction, however, not much later it is said that Skar king and all the other apes have been trapped in the under-secret realm and can't go out since Kong hasn't found him nor showed him the way out. So surely, is not possible that he destroy the outpost in the first place.