Continuity mistake: During the battle of Carthage there is a scene where Juba jumps on to the back of a moving chariot. When it cuts the chariot is suddenly standing still, Juba is standing on the ground while his mates are grabbing the gladiator on the chariot. (01:24:30)
Continuity mistake: At the end of the first battle in the Colosseum, Maximus puts his sword up to the crowd. There is blood at the tip of the sword, but in the following shot, it has vanished. (01:24:40)
Continuity mistake: During the enactment of the Battle of Zama, Maximus rides his horse around a bend with his sword in his left hand. When we cut to close up, it's back in his right. Looking at the left-handed shot in freeze-frame, you can see the frame has been flipped, left-to-right (check the armor). This was probably for continuity reasons. Similarly, Maximus jumps on the horse and his shoulder protector is clearly on his injured left shoulder. However, a few frames later, the protector is on his right shoulder, then it moves yet again back the correct spot, the left shoulder. (01:24:45)
Continuity mistake: When the gladiators have won inside the coliseum for their first battle, Commodus goes to see Maximus in the arena. In the previous shot, Maximus gets off of a white horse, yet in the following shot, the white horse is at the bottom of the screen with Maximus and the other gladiators some distance away. (01:25:35)
Continuity mistake: At the end of the first battle inside the Colosseum, Commodus goes out to see Maximus, yet when he first enters the arena's floor, the distance from him to Maximus changes three times during shots. For example, when he first goes through the gate, it cuts to Maximus, then back to Commodus and he is just coming out the gate again, yet in the previous shot he came out the gate. (01:26:15)
Continuity mistake: During the first gladiator fight in the Colosseum, Maximus picks up the arrow from the ground. His hand is covered in blood, but in the second camera shot, no blood at all, and then in the third shot, you can see the blood again. (01:26:25)
Continuity mistake: After the Gladiators are victorious at the Battle of Carthage, Maximus reveals his identity to Commodus. The time seems to change from sunset to high noon a number of times. The crowd shots are at noon, the close ups are clearly made with the sun on one side of their faces. (01:27:20)
Continuity mistake: When Maximus, Juba and the other slave are eating at a table, the big slave pretends he's choking. Juba has his hand on the spoon, yet when it cuts to the next shot, his hand is no longer there. (01:36:30)
Continuity mistake: In the scene where Hagen is faking a choke you see Juba holding his bowl of food with both hands. When it cuts back he is holding it in his left hand only. (01:36:35)
Continuity mistake: After Hagen has faked choking Juba start laughing. Then it cuts to Maximus slowly starting to laugh. In the next shot we can see both Hagen and Maximus laughing, but Juba is dead serious now. Then in the following shot behind Juba we can see him laughing again. (01:36:35)
Continuity mistake: When Commodus enters the chamber where he walks towards his father's statue, he has his hands hanging down. When it cuts his hands are folded. (Extended Version only). (01:38:15)
Continuity mistake: At the end of the battle with Tigris of Gaul, Maximus kills the tiger that leaps on top of him and throws it off to the side. In the next shot the tiger is back on top of him and he has to fight with it laying on his stomach. Later the tiger is once again off to the side. (01:42:15)
Continuity mistake: After Maximus and Tigris' battle, Tigris falls to the ground and we see his mask is already up. Maximus then pulls the mask up which has magically come down over Tigris' face again. (01:42:35)
Continuity mistake: In the battle scene between Maximus and Tigris, not only does the visor flip up and down (see above), but when Tigris falls down with his visor up, you can see that his face isn't marked. But when Maximus again unmasks Tigris, it's bloody with a giant scrape across the face. (01:42:35)
Continuity mistake: After the battle with Tigris of Gaul, Maximus' neck was spread with tiger blood. But when he faced Commodus, no blood on his neck. (01:43:30 - 01:44:30)
Continuity mistake: During the scene in which Maximus battles one-on-one with Tigris of Gaul (the gladiator that returned from retirement) in the Coliseum, Maximus is ordered to kill the Tigris. As he refuses and throws the axe down, the left side of Maximus' neck is completely covered with blood. When Commodus enters to speak with Maximus, there is only the slightest trace of blood on his neck, which now also seems to be completely dry. (01:43:35 - 01:44:30)
Continuity mistake: When we get to the comedy play fight between Maximus and Commodus, we look at the front of the stage and we see the actor playing Maximus is standing in the middle of the stage and the one playing Commodus on the right side. When we get a view from back of the stage 'Maximus' is standing on the left side of the stage and 'Commodus' in the middle. They have suddenly switched sides. (01:49:55)
Continuity mistake: When Commodus and Lucilla are lying in bed, after Commodus tries to seduce her for a kiss, he lowers his arm and says "You know I love you". When it cuts he suddenly has his hand lying on her shoulder. (01:57:40)
Continuity mistake: When Commodus tells his nephew Lucius about Roman history, the hairdo of Lucius changes a few times during the scene. (02:03:00)
Continuity mistake: When the Gladiators are fighting the Praetorians so Maximus can escape, they stab Hagen when he is on the ground. Notice that it is in a fast forward-like time. The Praetorians are moving really fast. (02:07:10)
Chosen answer: No, they are full brother and sister. They both had the same mother and father. Incest was not exactly normal at that time, but it stretches back within the imperial families as far as Caligula and possibly earlier. There is no evidence to suggest that the real Commodus was attracted to his sister, it was probably just included in the film in order to make the character seem more disturbed, and also as another reason why he would be Maximus' enemy (Maximus and Lucilla were, after all, once lovers).
The Doctor