Continuity: Although the assassin and the ambassador are seated in the same tier of boxes, the assassin's view of his target through the opera glasses is from below and not from across.

Visible crew/equipment: In the scene where James Stewart told Doris Day that he lied about the telephone call was from the hotel, Doris gets excited and James struggles with her on the bed. During that scene, you can see on the upper left corner a shadow of a microphone.

Continuity: Dr. McKenna is wearing a blue suit and hat during the bus ride in the beginning of the movie and then again as the family board the wagon and set out for their hotel. When the wagon arrives at their hotel and everyone gets out, McKenna's suit and hat have suddenly switched to light gray.

Revealing: During the interrogation after the Albert Hall assassination attempt, the telephone used is an obvious Western Electric American-made phone instead of a British-manufactured telephone, betraying the fact that the interiors for the movie were shot in Hollywood.

Continuity: Multiple errors with Bernard's stabbing. 1. The knife changes type after he is stabbed. 2. He is stabbed in the lower neck but the knife moves down into the middle of his back in later scenes. 3. The knife moves from his back to the ground without any noise at all. It's just there on the floor.