When Daniel prevents Ootah from executing the leaders of the first battle, Daniel slaps Ootah's sword hand with his trophy arrow. The arrow snaps, yet is whole in the very next scene.
At the end of the first battle, Daniel is wheeling on his horse as the enemy around him fall to the ground in fear, because he is seemingly unhurt by the arrow sticking out of his chest. But the arrow is not there in any of the long shots. It only reappears in Daniel's chest when he is shown in close-up.
The signatures while the contract is legally signed, are nowhere near each other in prior shots.
When Peachy and Danny travel with the caravan into the Khyber Pass, all of the camels are Arabian (aka dromedaries), rather than Asian (Bactrian) beasts. This is not an error. Despite their names, both species are present and available in their domestic form in eastern Afghanistan, where the Khyber Pass is, and have been for centuries before the events of the movie take place.
Records indicate that Lodges of Freemasons have existed since at least the late 1500's. Masonic legend traces their roots to the building of Solomon's Temple. There is a theory that the order has secretly existed for millennia, even back to the days of Alexander the Great. This movie treats that notion as if it were true as part of its "secret history."
The avalanche footage was clearly shot at a ski area, as many
ski tracks can be seen as the avalanche falls. Such tracks would be highly unlikely high in the Hindu Kush.
Billy Fish acts as an interpreter for Daniel and Peachy to the people of Kafiristan. In fact, Billy speaks Urdu to the Kafiristanis and they reply in Moroccan Arabic, two entirely different languages (this is due to the fact the film was shot in Morocco and Moroccan extras were used).
In the introductory sequence, Arabic writing is visible on a wall, betraying the fact that the scene was filmed in Morocco.
To get to Kafiristan, they would go through the Khyber Pass and turn north, but when they leave the caravan, they turn left (south) - in the wrong direction.
In Kipling's office at the beginning of the film, Peachy states that according to Herodotus (pronounced "Harry-odotus"), Alexander the Great defeated King Oxyartes and took Roxanna as his wife. Herodotus actually died about 70 years before Alexander was born, thus making him unable to recount facts about Alexander's life history.
The Kafiristanis worship idols and yet the prayers/religious chants they utter are standard Muslim prayers/religious chants. They clearly mention the name of Allah several times. Islam is a strictly monotheistic religion, being against the worship of idols. The extras used in the film were locals from Morocco, a country that is near 99% Muslim. Historically, Kafiristan is believed to have meant "land of unbelievers" because it's people refused to convert to Islam.
When they are feasting they refuse the alcohol because of their pact but while the sons are being offered Caine drinks from his bowl of alcohol.