The last three weeks of principal photography on JURASSIC PARK were devoted exclusively to shooting the T-rex scenes on the largest sound- stage at Warner Bros. Studio. Prior to filming, the T-rex rig had been transported to Warner Bros. without its outer skin attached so that Winston’s crew could test the hydraulics on stage before enclosing the mechanical armature in foam rubber.

After all the hydraulics were tested and hooked up, a crew stayed late one night to glue the foam rubber skin onto the construct.

One of the biggest problems the crew encountered during the scene was the effect the “rain” had on the animatronic T-Rex. The animatronic T-Rex (weighing 9,000 pounds and 40 feet long) was robotic, and thereby electrically powered. When the animatronic became wet, it would start not functioning properly. The “skin” of the animatronic T-Rex would soak up the water, which would cause its weight to change.

Furthermore, the T-Rex’s head would start to shake, forcing the crew to wipe the animatronic down with towels. This problem occurred several times as the T-Rex was constantly being rained on from the set.