Sylvester Stallone asked Chuck Norris to include a reference to The Chuck Norris facts (a popular internet meme) in the screenplay. Norris's wife Gena O'Kelly suggested him the one with the cobra. ("Chuck Norris was bitten by a cobra, and after five days of excruciating pain... the cobra died.")

Sylvester Stallone explained that his casting was looking particularly for actors who had not experienced recent hits: "I like using people that had a moment and then maybe have fallen on some hard times and give them another shot. I like those kinds of guys. Someone did it for me and I like to see if I can do it for them."

The film reveals that Gunnar Jensen earned an advanced degree in chemical engineering, then abandoned his science career to work as bouncer in order to impress a girl. Dolph Lundgren earned a chemistry degree from Washington State University in 1976, a chemical engineering degree from the Royal Institute of Technology in Stockholm in the early 1980s, and a Master's Degree in Chemical Engineering from the University of Sydney in 1982. Lundgren walked away from a science career to work as bodyguard for his then-girlfriend Grace Jones. While stuck in the mine, Gunnar refers to himself as a "Fulbright Scholar," which Lundgren achieved in real life.

This was Arnold Schwarzenegger's first film after he left the office as Governor of California.

While filming an action scene in Bulgaria, an explosion on a rubber boat killed one stuntman and left another in critical condition.

Continuity

During numerous shots, the plane has a rear access door (they load, and then throw out Jet Skis) but in other shots the rear of the plane clearly has no door, the latter being correct as this plane is a Canadair CL-215 which has no rear access.

When Booker is approaching Barney and his crew for the first time, Booker stops in front of Barney, in the next shot Booker comes to a stop a second time.

When Vilain has a gun at one of the Expendable's head, just after they find the box, you can clearly see he is holding the gun with his right hand. The close up reveals he is holding it with his left hand as his left finger is on the trigger, then the next shot shows him holding it in his right hand again.

When the team and the miners escape the mine near the end of the movie, everyone is seen leaving the mine with clean faces and clothing.

After the bar scene at the beginning of the movie, Barney is seen riding off on his motorcycle. The license plate of his motorcycle is showing on the left side of the rear wheel in the first shot and then on the right side in the next shot to be shown on the left side again upon arrival at this destination.



Factual errors

The guys are seen zip-lining down on a high voltage power line. This could never be possible, as on every pylon, the wire is anchored to an insulator. Even considering the fact that the power was turned off, they could have only zip-lined between two pylons.

Plutonium is about 20 times heavier than water, so the Plutonium bricks would weigh about 100 kilograms each. It would be impossible for one person to move that much weight as is displayed in the movie.

During the opening scene the bad guys are actually speaking Thai even though they are supposed to be Nepalese. Also the sub-titles don't actually match what they are saying.

The coordinates that show up in the binoculars; N39?93'19" E17?70'56" are not real coordinates, as the minutes (the second number) must be between 0 and 59. During the scenes the coordinates do change, even into an existing location, but that does not represent what he sees through the binoculars, but is in fact somewhere in the Ionic Sea, off the coast from Italy.

As the plane crashes into the mine, people and equipment are thrown to the back as well as debris from the tail. Actually, as the plane is reducing speed during the crash, unsecured people and equipment should have been thrown towards the cockpit. Only pieces that hit the mine's surfaces should be left behind.



Revealing mistakes

After the big fight at the airport, Booker, Church, Maggie and Trench are seen leaving in the helicopter. As the camera pans out on Barney, as viewed from the chopper, there is no wind gust at all and Barney's hair doesn't move from the vortex wind that would be created by the helicopter. Also in this situation you wouldn't be able to look at the chopper directly due to the wind vortex blowing in your eyes.

When the Canadair CL-215 takes off from the water through the smoke after the hostage rescue, there is no wing or prop vortex created in the smoke as the airplane flies through.

When the Expendables come across the wrecked aircraft, it is obvious that it is there due to having crashed. The engines are missing, which would be likely in a real crash, however it is obvious that the engine was removed by unbolting it, and not by crash forces. This is evident from the intact bolts and hoses shown forward of the engine firewall.

At the beginning of the movie, the guard on the left makes a very self-aware glance directly to camera. He's not looking at the other guard, but further left than that, into camera.



Miscellaneous

At the beginning battle of the movie, when Yin Yang is fighting the bad guys that attack him with knives, it is very noticeable that 1 of the attackers has a rubber knife.

Barney takes cover behind a car that could not protect him from assault rifles. Later in the film when he faces off Vilain he hides behind metal shelf and glass brick windows, both which would offer him no cover from assault rifle fire.

In the opening scene assault rifles fired by the good guys while they drive sound like machine guns.

Several references are made throughout the movie about the main characters playing in other movies: lone wolf (Chuck Norris), 'I'll be back' (Arnold Schwarzenegger), 'yippy ka'ee' (Bruce Willis).



Anachronisms

A US Postal Service mail drop-box on the "New York" Soviet training grounds has the Post Office logo adopted in 1993, which is post-Cold War.



Audio/visual unsynchronized

In the beginning scene when the Expendables are raiding the enemy territory and about to crash through a building, Gunner yells to Yin Yang "Watch your head, insect!", but if you watch his mouth movements, he was clearly saying something else at the time which was dubbed over with the new line.

After Barney meets Maggie for the first time under the bridge and starts his motorcycle, you hear the engine rev up before Barnie even touches the throttle.

When Christmas is dressed as a monk he says something in Latin, but his mouth never moves.

After the airport fight, Vilain and some of his men are seen arriving at the hangar on a lifted truck with a regular V8 engine sound. It's actually a Toyota Hilux and the 3.0 D-4D badge on the door means it's the 4 Cylinder, 3 Liter Turbo Diesel engine which sounds totally different.



Crew or equipment visible

During the shootout scene between Vilain and Ross towards the end of the movie, you can clearly see that Barney is wearing ear protection while he is taking cover from the bullets.



Errors in geography

At the beginning of the film, the location is stated as Distretto di Sindhupalchok, Nepal, however, signs written in Burmese can be seen.



Character error

Jensen writes Einstein's equation for general relativity on a napkin, not special relativity as stated.