Spielberg discovered the story by total accident. He was working on a script that would eventually become the hit television show ER with author Michael Crichton, who casually mentioned his new dinosaur book, prompting Spielberg to immediately buy the film rights.

The director was essentially forced to make the movie. Spielberg desperately wanted to direct his passion project, Schindler’s List, but the studio president would only give him the green light if he agreed to film his dinosaur blockbuster first.

A theme park ride inspired the original plan. The initial idea was to build every single dinosaur as a massive, full-size robot, heavily inspired by the King Kong ride at Universal Studios, but the team quickly realized it would be way too expensive.

The iconic logo was borrowed from the book. Unlike most movie adaptations that invent their own poster, the famous T. rex skeleton logo was taken directly from designer Chip Kidd’s artwork for the original novel’s cover.

A real hurricane shut down production. The cast and crew were trapped in their hotel when the massive Hurricane Iniki struck Hawaii during filming, and Spielberg actually used some footage of the real storm in the final movie.

The T. rex roar is an absolute animal mashup. To create that terrifying, bone-chilling screech, the sound design team recorded and blended the noises of a baby elephant, a snarling tiger, and a gurgling alligator.

The animatronic T. rex had a mind of its own. Because the giant robot skin soaked up water during the rain scenes, it would randomly shudder and twitch to life all by itself, completely terrifying the crew working on the dark set.

The famous rippling water cup was a nightmare to film. To get that iconic vibration as the dinosaur approached, a special effects expert had to lie on the floor of the car and pluck a guitar string attached to the dashboard.

An accident made it into the final cut. When the giant T. rex breaks through the plexiglass roof of the kids’ car, it was completely accidental. The robot hit the glass way too hard, losing a tooth and getting genuine screams of terror from the young actors.

The self-driving cars were a total illusion. The futuristic tour vehicles were not actually on a track. Instead, they were driven by a crew member who was hidden completely out of sight in the trunk of the car.

Dinosaurs barely have any screen time. Even though the movie feels packed with prehistoric action, there are only about fifteen minutes of actual dinosaur footage in the entire two-hour runtime.

The velociraptor noises are surprisingly awkward. If you think the raptors sound terrifying when they communicate with each other, you might laugh to know the sound designers achieved those noises by recording tortoises mating.

Harrison Ford almost took a trip to the park. Spielberg originally offered the lead role of Dr. Alan Grant to the Indiana Jones star, but Ford turned it down because he felt the part was not the right fit for him.

Jim Carrey auditioned for the chaotic mathematician. Before Jeff Goldblum stepped into his iconic leather jacket, comedy legend Jim Carrey actually read for the role of Dr. Ian Malcolm.

The ending was a massive last-minute change. The original script had the humans killing the raptors to escape, but Spielberg realized the audience loved the T. rex too much, so he rewrote the finale to let her swoop in and save the day.