The original screenplay was called Bloody Mary. The title was cleared in every territory except Japan, where the name Bloody Mary is copyrighted, and it was suggested that the title be changed to Dead Mary for release in that country alone. When the film's producers discovered that another film, also called Bloody Mary, was being readied for release around the same time, it was decided that the film's title be officially changed to Dead Mary in order to avoid confusion. This spawned an inside joke in the finished film, when the better-known game Bloody Mary is dismissed as being "the lame version" of Dead Mary.
The script originally featured an actual Bloody Mary who, when summoned by the mirror game, rose from the depths of the lake to murder the characters one by one. Director Robert Wilson decided that it would be more interesting if the evil force was never seen, but instead could manifest itself in any one of the old friends gathered at the cabin, thus making the film more a creepy paranoia piece and less a supernatural slasher film. However, many film websites still make reference to the film's original (and now incorrect) synopsis.