Continuity mistake: After the boy's Noel-Coward-lookalike father says, 'Et les fruits?', goes into the kitchen, and disappears out of shot, watch the cat on top of the bookcase to the left of the door. Before the boy runs into shot, the cat suddenly changes position and a mysterious lens flare appears on the right of the screen, showing that it's actually two shots edited together.
Continuity mistake: It is supposed to be night when Joe slips out of the hotel, but a daytime sky is visible.
Factual error: The movie is set in Cardiff but the Transporter Bridge seen at the beginning of the film is really in Newport.
Continuity mistake: After Sir Hugo has stabbed the girl on the moor, no blood is visible on the knife he used, however after he drops it (because he is attacked by a hound) blood has now appeared on it.
Other mistake: A police officer fires two shots, hitting a bank robber in the back. The "bullets" do not make holes in the robber's coat. All they do is create two tiny puffs of dust.