The film is in the Guinness Book of World Records for the costliest aerial stunt ever performed. Stuntman Simon Crane was paid one million dollars to cross once between two planes at 15,000 feet, without the aid of any safety devices or trick photography. The insurance company refused to insure a stunt man for this, so Sylvester Stallone offered to reduce his own fee for the movie by the amount that the stunt cost to produce in order that the film could be made.
Sneak-preview audiences saw a scene where a rabbit gets killed by gunfire. Their reaction was strong enough for Sylvester Stallone to invest 100,000 dollars of his own money to have the scene re-shot, so that the rabbit escaped.
Electrical storms hit during filming, knocking down five crew members. Climber Earl Wiggins was hit three times, but was only slightly injured. During a later storm, crew members had fun taking pictures of each other with their hair standing on end while the climbers pointed out the wisdom of evacuating.
Ron Kauk was Sylvester Stallone's stunt double and really had to bulk up. He ate 5 carbohydrate-heavy meals a day and pumped a lot of iron. The trainer wanted to have him eat a sixth meal in the middle of the night. Kauk also doubled for Leon, and Janine Turner.
Carolco had originally signed Sylvester Stallone to appear opposite John Candy in a comedy directed by John Hughes about feuding neighbors. When the project was dropped, Stallone was persuaded to appear in Cliffhanger.
Set in Colorado, but filmed in the Cortina d'Ampezzo-Dolomites mountains, because of their spectacular similarities to the Colorado Rockies. The production paid 80,000,000 Lire to enter all mountain areas.
The stuffed puppy that falls off the cliff in the opening scene was not scripted but was added at the last minute. Renny Harlin liked the dog so much he bought it so that the audience would have a clear idea of what would happen and how horrific the fall was.
The movie's most breathtaking scenes were shot in the Cortina d'Ampezzo Dolomites mountains. The bridge scene was shot on Monte Cristallo - ferrata Ivano Dibona. The crew stayed in Cortina more than 3 months. Further filming took place in Durango, Colorado. The credits of the film also thank the Ute Tribe for filming in the Ute Mountain reservation.
In the original cut of the film shown to test audiences, there was a 40-foot jump from one cliff to another that Sylvester Stallone's character performs. This scene appears in the theatrical trailers to the film. It was cut because test audiences laughed out loud when they saw it and thought it was totally impossible. The clip of the jump was redone and used for a shorter jump off a cliff near the end of the film using computer graphics and special effects.
The two-story high cliff built for the climactic battle sequence burned to the ground completely in eight minutes when the miniature helicopter explosion got out of control. The heat of the fire was so intense it melted one of the cameras.
Sylvester Stallone and Renny Harlin were originally going to make a film titled "Gale Force" for Carolco Pictures. The script for the film had the main character, an ex navy-SEAL, fighting a group of modern pirates/thieves in a coastal town during a large hurricane. Despite working on it from 1989 until 1991, Carolco deemed the project too expensive to produce (after investing over four million dollars in script rewrites plus the original script) and because the planned special effects for it proved to be too difficult at the time, the plug on the project was pulled. Stallone and Harlin then decided to make Cliffhanger instead, although Harlin was already paid three million dollars for directing Gale Force, he didn't have to return the money. Surprisingly enough, Carolco estimated that budget for Gale Force would be around forty million dollars, and the final budget for Cliffhanger turned out to be seventy million dollars.
In the cave of bats scene, the 'bats' seen on screen were actually added after filming as a special effect. Real bats were brought in to fill the cave, but Sylvester Stallone and Janine Turner were too afraid to shoot the scene with live bats.
Tri-Star/Carolco planned a sequel in 1994, called "The Dam", which was described as "Die Hard in a dam" and would have Sylvester Stallone's character from Cliffhanger fighting terrorists who took over Hoover Dam, but it never went beyond the development stage. Stallone tried to resurrect the project again in 2008, but it never happened.
An avid golfer, Sylvester Stallone found that climbing roughed up his hands and consequently messed up his game. He had a net on the set for practice. The models he was dating complained about his rough hands.
After Michael France sold the "Cliffhanger" script to Carolco Pictures for 500,000 dollars, the company was visited by two independent producers, Gene Patrick Hines and James R. Zatolokin, who provided proof that France was not the originator of the story. It turned out the idea had been first developed in the 1980s by Hines and a world-famous climber and author John Long. Carolco agreed to pay Hines and Zatolokin a producers' fee of 400,000 dollars and gave them co-producing credit. John Long received a "Based on a premise by..." credit.
The film has been criticized for its unrealistic portrayal of rock climbing. One example is the feature of the bolt-gun which fires bolts directly into rock, forgoing the usual rock-drilling and bolt-hammering used in rock-climbing. This ignores certain material properties of rock that should cause the bolt-gun's impact site to shatter and explode with flaky projectiles. The bolt gun is considered the most serious of the film's technical inaccuracies. Further examples are showing athletic moves, which have no use in real climbing, or free soloing with - then also completely useless - gear.
The trivia item below may give away important plot points.
In the opening scene where Sarah slips from Gabe's hand had to be done several times because Sarah's glove would not slip off as desired. In order to get it to slide off, director Renny Harlin had her wear a glove that was a couple of sizes too big and filled the glove with Vaseline and even then Sylvester Stallone's grip was too tight and the glove almost stayed on.