Revealing mistake: When Agamemnon finds Briseis kneeling, while Troy burns, he pulls her up by her hair. As she lifts her left arm up, the beige undergarment she wears is visible under her arm. From the moment we see Briseis kneeling, throughout this entire scene, the set lighting and shadows change quite dramatically in consecutive shots. (02:27:05)
Revealing mistake: When Briseis sticks the knife in Agamemnon's neck, you can plainly see silver fillings in his teeth when his head is back. (02:27:40)
Revealing mistake: Just as Achilles is hit with the fourth arrow in the close-up, on the left side of the screen, beside the statue, something suddenly appears in the shot and then disappears. (02:28:40)
Revealing mistake: When Paris hits Achilles with the fifth arrow, as Achilles raises his right arm, the two round yellow stickers on both sides of his armor beside the studs, near the arm holes, are perfectly visible in this and the following two extreme close-ups. They are used to mark the bottom edge of the shot. Obviously they are gone in the previous and following shots. (02:28:50)
Revealing mistake: When Achilles is dying and saying farewell to Briseis, when the camera is facing Achilles, you can see the netting on Briseis's wig underneath her "hair". (02:29:25)
Revealing mistake: When the body of Achilles lies on the pyre in the close-up, although the fake body has a similar appearance to the real Achilles, some things are different, such as the body does not have the distinctive circular scar on the left upper arm as Achilles did. (02:31:40)
Revealing mistake: Achilles is hit with the final arrow that Paris lets loose, and he drops down to his knees. As he kneels on the grass his left ankle and foot are perfectly visible, and the arrow in his ankle/foot is unequivocally gone! (Visible on VHS.)
Revealing mistake: The dawn after the Trojans have retaliated against the Greeks with their fiery assault on the beach, a light filter was used to make a midday shoot appear as though the sun had not fully risen yet. This is evidenced by two things. First, the shadows are not as "deep" as they would be at that time of day. All the details that shouldn't be visible at dawn are perfectly defined, it's just not bright. Second, the fires that still burn should be radiating a bright orange glow. Instead, they are just as dimmed as the rest of the light.
Revealing mistake: When Achilles stabs Hector, you can actually see the sword vanish from Achilles hands just before the shot switches to the side view of the killing.
Revealing mistake: When we fly over the beach and see all the ships with the arriving troops, some running ashore, the CGI men look like they're running on the water's surface rather than through it, as they're making no splashes.
Revealing mistake: When the soldiers of Greece are collecting the wood for the Trojan horse, you see bits coming of the wood, revealing the white Styrofoam used to make the wood.
Answer: They didn't know the Greeks weren't bringing cavalry. The Greeks did use them and sometimes brought them by sea. It was there to stop a cavalry charge and to break up fighting formations.
LorgSkyegon