In the G-8 Conference on Diamonds,Belgium shown in the beginning, most of the participants are seen using modern day laptops. Also shown are modern day LCD monitors which were not in market during the late 1990s when the film is supposed to take place.
When Danny arrives to do business with Commander Zero, he encounters Rambo, who wears a Snoop Dogg Afroskull Tee under his military green shirt. This piece was fabricated by Alstyle Apparel & Activewear in 2004.
Maddy uses a Leica 35mm M6 rangefinder camera with a Leica Summicron 35mm f/2 lens. When she shoots, the soundtrack clearly uses a Single Lens Reflex (SLR) noise. The distinctive sound is because a mirror is tripped when an SLR takes a picture. The Leica M6 has a cloth shutter and makes a very different and quieter noise.
When Solomon enters the rebel camp to find Dia, Archer, armed with a Kalashnikov taken from a sentry, moves into position to cover him. Once in a position with cover, his rifle is heard cocking, yet his hands do not move.
At "G8 Conference" scene an official says that people in Africa have died over "ivory, rubber, gold, oil and it's now true of diamonds". Oil is produced in very small amounts and never been a matter of any wars. Diamonds haven't caused much war in South Africa and Botswana since the end of 19th century. And civil war in Sierra Leone wasn't over diamonds. Diamonds were used to finance it, though.
In the Freetown prison, there is a tattoo on Danny Archer's right shoulder of the SADF 32 Battalion's badge. While it has the Cape Buffalo and two crossed arrows, the two scrolls with the battalion's motto - "Proelio Procusi" - are missing. The arrows are also misplaced. In the tattoo, the arrowheads are directly underneath the tips of the buffalo's ears, while the actual badge had the heads directly under the bases of the ears, where the ears met the animal's head. The arrows were placed where the scrolls should have been.
When RUF raids Solomon Vandy's village, RUF soldiers start chopping people's hands. At this scene, the RUF commander shoots a person who tries to run. After that, he explains their motive to the second person. At this time he has a sword in his right hand and a book in his left. From the back camera, the sword is in the left hand, and the book is absent. Also from this point, the book goes in and out of the commander's pocket every now and then till the next scene.
When Solomon is carrying the child back to the van, in the scene where the journalist jump out of the van to report on a roadside attack, the child's arm position changes a few times, from around Solomon's neck to his side, and back again.
When Solomon goes to hide the diamond for the first time, he is seen bending down to take the diamond from his toes. When he opens his toes up, there is nothing there before it cuts to him pulling the diamond from his toes.
The GPS coordinates of the rebel camp that Danny Archer gave when he called in the air strike puts the camp somewhere in the southeastern Sudan, near the Ethiopian border - on the other side of the African continent from Sierra Leone.
When Solomon and Archer are fighting overhead power lines can be seen. However, there are no power lines or utility poles on the road they follow through the jungle. These power lines appear twice during the fight.
When Danny tells Maddy the "story", he, among other things, says: "By the time they get to India... they become like any other diamonds". India and Indonesia specialize on the smallest diamonds only, while the diamonds shown in the film are way beyond their "preferred" size - each diamond shown is at least 10 carats.
Towards the end Archer is making a call on a satellite phone. He is holding and moving it around like a normal cell phone, while satellite phones need to be pointed with the antenna towards the approximate satellite location in the sky.
When Danny tells Maddy the "story", he, among other things, says: "By the time they get to India... they become like any other diamonds". Two goofs in one. First - diamonds cannot "become like any other diamonds". Crystal structure, color, shape - any diamondeer can tell where the diamonds come from. And second - India and Indonesia specialize on the smallest diamonds only, while the diamonds shown in the film are way beyond their "preferred" size - each diamond shown is at least 10 carats.
The mercenary intervention in the Sierra Leone civil war (Executives Outcomes PMC) began in May, 1995 and ended in January, 1997. They were long since gone by the time of the RUF invasion of Freetown in January 1999 when the movie is set. It was actually a combination of British and UN troops who brought the war to an end in 2001. Possibly made deliberately to avoid associating EO with the fictional mercenaries, whose activities were much more sinister.
In the beginning of the film, Danny Archer gets arrested by Liberian border guards while crossing the border from Sierra Leone to Liberia. He would therefore end up in a prison in Liberia and not in Sierra Leone where he meets Solomon.
It is very unlikely that a huge multinational corporation big enough to be invited to G8 meeting, will want to bother over one diamond, even a big one. They make most of their produce from mêlée - medium sized diamonds between 0.5 and 2 carats.
In the scene where the mercenaries take away the child in their truck, as the boy reaches outward for his mother you can see his arm knock the magazine from the left soldiers AK-47 assault rifle, which subsequently flies off-screen.
The goof items below may give away important plot points.
Although set in 1999, when Solomon and Maddie are in London
towards the end of the film, we see a single deck red "bendy" (articulated) bus showing route 453. Neither this bus type nor this route existed in London until 2003. A 2005 Volkswagen Passat also drives by.
At the hotel that Solomon Vandy works at, we see him bringing 2 pieces of luggage and resting them near the back of the vehicle. He only puts one of them in the trunk, closes it and opens the car door for passenger.
At the end of the movie when the pink diamond, now cleaned and mounted, is being placed into a vault drawer, the diamond shown appears to be almost twice as large as the same diamond depicted in previous scenes.