Visible crew/equipment: When Hector is on his knees, at the start of the first shot as Achilles leans forward to plunge the sword into Hector, there are shadows on Achilles' skirt, knee, etc., that are not caused by either Achilles or Hector, but are obviously cast by crew and equipment.
Continuity mistake: In Sparta, when Paris enters Helen's room, she faces him and says, "You shouldn't be here," When she turns around to face the wall, now there are short curls at her forehead and the hair curls at the sides of her face are now curlier and neater. Then when she is standing in front of Paris with her hands at her sides, in the two shots facing her, her hair goes from the front of her shoulders to behind, and the cute curl at her forehead is gone. This type of thing occurs throughout the film in consecutive shots.
Continuity mistake: When Hector stops Helen from leaving during the night, her cheeks and the area around her eyes are both very red, and her eyes are tearful with tears down her cheeks. In the shot from behind her, when she briefly turns round her cheeks are not red or wet and though her eyes are teary, they are not as teary and red as the shots facing her.
Continuity mistake: In the scene near the beginning, where Achilles is standing at the palace where the golden statue is, he throws a spear into one of Hector's men. When the shot goes to him, you can see that he has his left arm stretched out; you can see his hand. Yet when Hector rides on, the soldier on the floor now has his arm beside him and not outstretched.
Revealing mistake: When Boagrius throws the first spear in the shot facing Achilles, Boagrius leans in to throw it and then stands straight just when the (CG) spear nearly reaches Achilles, who still has his shield at his side. In the next shot facing Boagrius the (CG) spear is still near Boagrius, who stands straight, and Achilles raises his shield for the incoming spear. This spear casts a (CG) shadow as it heads toward Achilles and when the ('real') spear tip penetrates Achilles' shield, there are other (CG) spear shadows on the ground heading toward Achilles - but NO spears.
Revealing mistake: Odysseus normally has wavy/curly hair that reaches the base of his neck, yet just before Hector cuts Patroclus' throat, when Odysseus' helmet slips forward as he fights and the white cap is visible, his hair is very short and straight in back. It's also apparent earlier, when he visits Achilles in Phtia.
Continuity mistake: After the Greeks climb out of the 'Trojan' horse, some run to the front gate. There is a long rope hanging on the left side of the gate, the base of the left stone pillar that holds the flame is aligned with the edge of the huge gate's door frame and the pillar stands perfectly upright. However, as the camera pans to the left, when the soldiers start to run up the stairs on the left, the rope is gone, the actual tall stone pillar with flame is moved at least two feet and it now stands very crookedly. (This has nothing to do with camera angles.)
Continuity mistake: While in Phtia after Odysseus says, "My wife will feel much better...I'll feel much better," Achilles takes the sword out of Patroclus' hand and then pats him on the bottom with his own sword. As he does this in the shot from behind Achilles, the ground area in front of the bushes is sword free. However, as Odysseus says, "A thousand ships," there is a sword lying on the ground in front of the bush. This is either a continuity error or simply the lack of sound of a sword being thrown to the ground, since it's likely to be Patroclus' sword that Achilles threw.
Continuity mistake: Achilles stabs Hector in the chest in their climactic battle. Hector, dying, falls to his knees and falls onto his right side with his arm underneath him. Achilles goes to his chariot and returns with a rope. Hector now has his right arm stretched out with his head lying on it.
Factual error: When King Priam is showing Paris the Sword of Troy we get a close-up view of the blade and it looks suspiciously like steel or polished iron, as do a lot of the weapons which we see in this film. However, at the time of the Trojan War, civilization was still very much rooted in the Bronze Age and iron weapons would not have been available. Iron weapons were first used by the Philistines around 1100 BC, some years after the Trojan War, and it was still another several hundred years before this technology was ever used.
Continuity mistake: When Glaucus, Paris and other Trojans stand at the ready, the Greeks break through the palace gates, stream into the room and begin to fight. However, after Paris runs up the stairs, pulls and releases the arrow to hit the soldier's neck, in this shot Glaucus and the Trojans stand on the opposite side facing the Greeks, they have not yet even begun to fight.
Revealing mistake: When the soldiers' bodies are being collected in front of Troy's gate, after the battle, the pattern of the real stone wall (the set) on the left of the gate and all the soldiers that stand atop this wall, delightfully repeats, over and over, on the CG stone wall farther to the left.
Continuity mistake: When Hector grabs the sword from the ground, prior to stabbing Ajax, the blade is covered in blood. But when the blade tip touches Ajax's armor, before it pierces him, the amount of blood on the blade is significantly decreased.
Continuity mistake: During Achilles and Hector's duel, in the wide shot Hector uses his shield to shove Achilles' spear tip down to the ground, beside his right foot while his left foot is way behind him. However, in the next close-up as the spear tip is still on the ground right behind Hector's left foot, his right foot comes forward to snap Achilles' spear.