This film (along with several others) is somewhat based on the story of US Marine Corps sniper Carlos Hathcock, who took out a Viet Cong sniper who was stalking him by firing a round through the man's scope, sending the bullet into his brain. The story has been labeled a "myth" by some, but the incident was observed by Hathcock's spotter, John Roland Burke, who surveyed the scene after the kill. Given the flight time of rounds at long ranges, both snipers could easily have killed one another. The enemy rifle was recovered and the incident is documented by a photograph. After an investigation, the Marine Corps confirmed the incident and registered the kill to Hathcock.

The Japanese release was titled 'A Mountain Cat Never Sleeps'.

If you look closely at the locomotive of the train that inserts Beckett and Miller, the QR symbol of the Queensland Rail can be seen on the side. Queensland was the state of Australia where this movie was shot.

The film was marketed two different ways. The international trailer--produced by the independent financiers behind the film--focused more on the psychological and thriller elements of the story and showcased the struggle between Beckitt and Miller. The US trailer, cut by TriStar, who picked it up, was accompanied by the muscular score from Terminator 2: Judgment Day (1991) and focused more on the action elements, highlighting the chase and shootout sequences.

The weapon used by Billy Zane in this movie is not an H&K PSG-1, an expensive precision semi-automatic rifle commonly used by Special Forces snipers. It is an H&K SR-9 TC, a similar but cheaper version of the PSG-1 that was designed for civilian sales.

Continuity

When Beckett is using the sleeping Miller as bait, the knife that is seen bobbing in the water is different than the one Beckett later removes. The one that distracts the enemy sniper is a cheap "survival" knife, while the one Beckett is seen untying is a Marine Corps fighting knife, or "Ka-Bar".

The camouflage paint on Miller's face changes continuously throughout the movie.

When Miller loses his balance, slides down the slope and into the water, the overhead shot clearly shows the rifle dipping into the water. When the shot then moves to being in the water with Miller, he's holding the rifle above his head, keeping it dry and protected.

After Beckett's spotter gets shot by an enemy sniper in the beginning, the blood on his chin appears, disappears, and finally appears again.

When Miller kills El Cirujano you clearly see a bullet hole in his forehead but in the next scene when he falls backwards there is no hole in his forehead.



Factual errors

When Miller is firing his weapon at his shadow at the church and the weapon runs out of ammo you can hear numerous clicks of the firing pin as he pulls the trigger. With the model of weapon he carries once it is empty the weapon will not dry fire.

When Miller prepares to shoot the drug runner on the boat, Beckett tells him to adjust his scope two clicks right. Miller uses the knob for two clicks in elevation.

Upon hearing AK-47 fire in the jungle, Miller says that he recognizes the "hammer recoil". No such thing: hammer strike has anything to do with a weapon's acoustic signature.

When Miller is flying in the Huey (UH-1) with the two soldiers (approx. 19 min in) the two soldiers have their weapons pointed up. Weapons are pointed down when flying in case of an accidental discharge.

Both of these snipers are guilty of letting their rifle barrels stick out from where they are concealed - Beckett in the brush and Miller between the slats in the storage shed. This is a definite no, no. A Sniper should always position his rifle back away from any opening that he is going to fire thru.



Incorrectly regarded as goofs

In the beginning of the film, Beckett and a helicopter crew chief exchange dialogue without the use of microphones. A Huey with open doors would be much too loud for them to have a conversation. The crew chief would hear nothing Beckett said because he is wearing an aviator's helmet.



Miscellaneous

A basic typographic error in the closing titles sees Michael J. Harker listed as the "Post Prodiction Supervisor."

At the start of the movie, range was estimated to be 650m, yet people could be heard talking and the target's name tag and rank could be read. At 650m you wouldn't be able to hear anybody talk, much less be able to make out a name tag and rank. The distance across the road to the store would be no further than 50m.



Audio/visual unsynchronized

When the Robinson R22 lands and throttles down, the sound is of a turbine helicopter spooling down, Robinson R22 helicopters have piston engines.



Errors in geography

When Beckett and Miller are getting on the train, the Queensland Rail symbol, QR, is clearly visible on the side of the carriages.

The QR logo on the train (the Kuranda Railway) is a dead giveaway that the location was North Queensland, Australia and not the jungles of Panama.



Character error

Beckett is a Master Gunnery Sergeant in the United States Marine Corps. However, the crew chief of the helicopter that extracts him in the opening scenes calls him "Gunny". The term "Gunny" is used as a familiarity with Gunnery Sergeants only, and a Master Gunnery Sergeant would NEVER be addressed as such.

Beckett is seen to be "deburring" a round with a knife. A real sniper would never do such a thing. Any alteration to the jacket of the round would alter the ballistics of the round (possibly quite severely). If anything, a rag would be used to wipe the round down. And if handled correctly, a match grade round wouldn't have any burrs.

Billy Zane's character Miller is called Zane in the common room.