In one scene, we are clearly told that the dinosaurs couldn't breed on their own because they are all female. We later find that, in fact, since they used frog dna to create the dinosaurs, they can in fact breed. Why was so much importance put on this aspect?
In the original novel, Alan Grant make a big issue about how insanely irresponsible and dangerous it was to introduce dinosaurs back into the world. John Hammond dismissed his concerns, saying the dinosaurs couldn't escape from the island, couldn't breed, and couldn't even survive without a special diet fortified with amino acids. So when it was revealed that the dinosaurs actually could breed, it wasn't so much a "behold the miracle of life" moment as it was a major "how could we have fucked up so bad?" moment. I seem to remember that they were going to stop everything else until they could get an accurate count of the dinosaurs, and an accurate count of every eggshell on the island to make sure there were no hatchlings unaccounted for.
This was all pretty much dropped in the movie.
It is one instance that explains everything that happens throughout the movie.
From the dinosaurs escaping to the dinosaurs breeding, much of the events that happen throughout Jurassic Park are meant to prove Dr. Malcolm right when he said "life finds a way."
In this specific example, the Jurassic Park scientists are "spared no expense" and years of research was conducted whereby they did "...things which nobody's ever done before." But we learn that in spite of this massive biologic and engineering feat, where so much deliberate science was conducted to prevent pretty much everything bad that happened in the film, life found a way anyway.
If I remember correctly from the novel the computer system managing the park were designed to count the number of animals of each type in the park, and to report if that number ever dropped unexpectedly (presumably denoting an escape).
At one point in the novel I believe Dr. Malcolm asks them to run a scan for more animals than expected rather than less. This is when they discover an increased number and so learn that the dinosaurs have been breeding.
I don't remember that element actually being in the film, but it's been some time since I've seen it.