As the end credits appear on screen, an announcer's voice is heard: "The management of this theater suggests that for the greater entertainment of your friends who have not yet seen the picture you will not divulge to anyone the secret of the ending of Witness for the Prosecution."
Before the film begins, a message appears onscreen saying that to avoid ruining the effect of the surprise ending, patrons should not take their seats during the last few minutes of the movie.