Visible crew/equipment: In the fight scene on the stairs near the end of the movie, the camera shot looks up and there is a security camera mounted up in the corner.

Continuity: In one extended scene, Chris O'Donnell is talking with someone. Almost every time the camera comes back to him, the ties on his shirt are first crossed, then uncrossed, etc.

Continuity: In the scene where Chris O'Donnell and Kiefer Sutherland are riding in the forest together, they are both on white horses. Kiefer Sutherland's white horse gets killed, and he later rides into Calais on a brown horse. In a later scene when the four are riding together to gather all the Musketeers, there are sometimes three white horses and one brown horse, and sometimes there are four white horses.

Factual error: Not long into the film, D'Artagnan jumps in some hay. There's a flag of the province of Québec (Canada) visible in the background. This film is set in France at a time this flag didn't even exist.

Other: In the scene where Chris O'Donnell is going to rescue the two damsels being chased, he dismounts from his horse that is already tied to the cart and ties the horse with the other rein.

Continuity: When D'Artagnan meets Porthos he accidently spills wine on Porthos' sash who then gets up and is seen holding the sash between 2 fingers. The camera angle changes and he is now seen with the sash just laying in his palm and then he's seen again with the sash between his fingers when the angle changes again.

Continuity: When Aramis is trying to escape from the husband of the woman he is reading the bible with, the husband manages to fire 2 bullets from his gun without reloading.

Continuity: When D'Artagnan is riding away from the brothers in the beginning, he is seen riding the horse into woods from the wide camera angle, but when the angle changes to a close up, you see D'Artagnan riding along the edge of the woods for a few feet and then turning into the woods.

Continuity: When the patrol goes into the house and finds Athos and Aramis sitting at the table, Aramis is cleaning his sword with a cloth up to the middle, and the rest of the sword is covered in blood. They converse a little, and when Rochefort steps forward (and Aramis says "Ah, hello again, Cyclops"), Aramis places his sword on the table, although now there is no blood on it at all. He had no time to clean it off, and even if he tried there is not sufficient blood on the cloth to suggest he did.

Factual error: When the Musketeers appear to save D'Artagnan from execution, Porthos says "this axe was a gift to me from the Tzarina of Tokyo." Although this lie is a reference to an earlier outrageous claim that he'd made at their first meeting, it would be impossible for him to make it, since Edo was only renamed Tokyo in 1868, and the film takes place some two hundred years before.

Revealing: When Porthos shoots the assassin with a crossbow, he is a good distance below him. But when you see the assassin grab the bolt, it is straight in his body as if he'd been shot level.

Continuity: In the scene where the Musketeers flee the city in a stolen carriage, looking out the window trees can be seen flying by, but in the very next shot, they're still in the city.

Continuity: Near the end of the movie, when D'Artagnan stabs Rochefort, D'Artagnan collapses on the floor and drops his sword. Constance grabs his hand and you can see a shot of the sword. Where is the blood on it?

Continuity: At the beginning, when Rochefort walks out onto the balcony to address the Musketeers in the courtyard, the guard on Rochefort's left obviously changes halberd/pikes between shots as they are completely different.

Continuity: When Aramis is wooing the wench, her hair changes from shot to shot. When he first speaks to her, she has small wisps on her left side. When the shot changes to D'Artagnan's point of view, she has a lot more hair down on her left side. As she leans to Aramis to kiss him her hair is down on the left side, and the shot of her kissing him shows her hair behind her ear.

Revealing: It was obvious that Chris O'Donnell didn't sword train with his stunt double. His fighting style in the close up shots is completely different from his doubles style in far shots.

Continuity: In the scene where D'Artagnan is being chased by Gerard after the duel for his sister's honor, as they approach the overpass stunt that ends with Gerard falling on his high-pitched butt, the swords at their waists disappear and reappear while changing positions on the horse.