Visible crew/equipment: When James Stewart tells Doris Day that he lied about the telephone call being 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.
The Man Who Knew Too Much (1956)
1 visible crew/equipment mistake - chronological order
Directed by: Alfred Hitchcock
Starring: James Stewart, Doris Day, Brenda de Banzie, Bernard Miles
Continuity mistake: 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.
Edward Drayton: Remember, you will only have time for just one shot. If you need another, the risk is yours.
Rien: I don't take risks.
Trivia: Alfred Hitchcock makes his regular cameo watching a group of street entertainers.