Continuity mistake: When the Doctor is talking to the Voice Interface Amelia, when he starts saying that "Scotland's never conquered anywhere, you know, not even a Shetland", his left arm, which was stretched out along the railing in the previous shot, is suddenly lowered. (00:27:28)
Revealing mistake: Mels is shot in the stomach by Hitler, leading to her regeneration. Rory, when checking the wound, says he's going to try and stop the bleeding. However, when she stands up while glowing with regeneration energy, and in every scene afterwards where Mels/River is wearing that dress, there is no bullet hole or bloodstain visible.