Who Done It? (1956)

Revealing mistake: When Frankie punches Barakov, pushing him through the window, not only can you see the wires lifting him, but it is obvious that the inside of the building is a studio set. The wall above the window gets torn - the wall is obviously made of paper and the scenery outside is a painted backdrop. But when the shot changes to outside the building only the window is broken and the wall is intact.