Continuity mistake: After being chased by soldiers after talking to his uncle, Dastan gets into a swordfight with Garsiv. As soon as it starts, Garsiv hits a pillar with his weapon knocking a significantly large chunk and a another smaller chunk out of it. In the immediate shot, the size and locations of the two chunks differ.
Other mistake: In the scene where Temina pretends to have fainted and Dastan runs over to her rescue, you can see Dastan wearing some kind of adidas/nike/other modern sport shoes, only the shoe sole is visible but you can see it very as he runs and kneels just before he gets whacked on the head.
Continuity mistake: When Ben Kingsley places the dagger in the sand crystal time goes backward. Tamina calls out Dastan's name and then he calls out her name in the same order as it happened in forward time. This should have been backward.
Continuity mistake: While storming the eastern gate of Alamut, Dastan climbs up onto a high beam with some rope. He then ties the rope round the beam and in one shot, the part of the rope that Dastan is holding onto is on the left hand side of the beam. The shot then pans out and in the next close up shot, it is on the right hand side of the beam.
Continuity mistake: In the scene where Dastan kills himself in front of his brother he does so by stabbing himself in the heart with his right hand wile holding his brother with his left. When we moments later get to witness this scene in reverse we can see Dastan using both hands to stab himself.
Continuity mistake: When Prince Dastan began to flee from the Persian soldiers after his talk with his uncle, one of the soldiers cut Dastan's left arm, with a noticeable bloody cut. But after Dastan escaped the soldiers and leans against a wall, the cut and the blood was gone, with his left arm undamaged.
Continuity mistake: While Dastan is securing the second gate in the battle for Alamut, a ring appears on his finger. While he is levering the gate, there are no rings on his finger. A moment later, when he waves at Bis to signal the gate is secure, he wears a silver ring on his left hand. The ring is visible again when Bis waves his torch at him, but is gone the next time we see him.
Continuity mistake: When Dasdan meets with his uncle and is showing him "the dagger", Ben Kingsley's hands are unblemished, they only appear burned when Dasdan notices them.
Visible crew/equipment: in the scene where Dasdan is being chased from the palace and he releases a bunch of horses: As the group of horses preceeding him passes through the gates, with a front camera angle, a rider in black is seen mounting and riding one of the horses, probably a horse trainer.
Continuity mistake: In the scene where Dastan and Tamina are again captured by Sheik Amar, Seso, and their group because of the chaos they caused back at the valley. In the oasis, watch Dastan's left arm carefully: the leather belts are changing shot by shot. In one shot there are many black strips across, and in another shot we see it's a single black strip running around his arm.
Continuity mistake: When Tamina is berating Dastan on acting like a typical Persian prince, her hair is to the side and in front. After Dastan explains how he came to be a prince, her hair is swept to the back.