Continuity mistake: When Godfather Drosselmeier walks into Marie's bedroom before he tells her the story, the bedroom door opens from the left, but after Marie's mother brings her the breakfast tray the door now opens the opposite way, from the right.
Continuity mistake: In Marie's bedroom, the finials atop the tall cabinet beside the door appear and disappear, and when Marie gets out of bed while Nutcracker and Mouse King duel, the cabinet now has an additional pediment.
Continuity mistake: After the bell is rung, when Marie and Fritz rush over to their parents the tall cabinet has a flat top, but once the toy castle is uncovered there's a pediment atop the cabinet, which vanishes and reappears in following shots.
Answer: The original 1816 story "The Nutcracker and the Mouse King" by ETA Hoffmann features the seven-headed Mouse King. Since then there have been numerous adaptations and re-imaginings of that story in literature, on stage and screen in different forms. In the classic versions the Mouse King has seven heads wearing seven crowns, other versions he has only one head, and in a few versions three heads. In the original and other adaptations the number seven is specified several times: Marie Stahlbaum is seven yrs old; the seven-headed Mouse King; the seven steps backwards; seven little crowns. The makers of this animated movie chose to feature the classic Mouse King.
Super Grover ★