Continuity mistake: At the very beginning of the duel scene you can see Roan extract his mother's sword from the sheath a guard is holding for him, then turn around and step towards the center of the arena. Several seconds later, in the shot of Lexa right after Clarke's arrival, you can see him in the background unsheathing the sword once again. (00:28:00)
Continuity mistake: At the very beginning of the duel scene, Roan starts running towards Lexa holding his sword in his left hand. In the following shot he can be seen running with the sword in his right hand, while when they finally collide he's back to holding it with his left. (00:28:25)
Continuity mistake: At the beginning of the duel scene, when Roan and Lexa lock swords, they do so with each sword pointing to their holders' right. During the shot of Lexa being forced to her knees while Roan tells her to get down, though, both swords are pointing to their holders' left, and Roan can be seen holding his with his right hand instead of his left like he does in the rest of the scene. (00:28:40)
Continuity mistake: During the duel scene, after Lexa smacks Roan flat to the ground, he lands with his right hand right upon one of the swords. In the following shots, the sword changes position and can be seen at various distances further to his right. (00:30:10)
Continuity mistake: During the duel scene Lexa's face gets smeared with black blood following a few hits, but in the shot when she announces "The Queen is dead" right after she kills Nia, Lexa's face is suddenly clean. (00:30:55)
