In the "San Chome no Yuhi", the character of Rokuro Hoshino is a young boy. In this film series, the character is a girl named Mutsuko Hoshino.
Just before opening title, Ippei spins the propeller of his toy plane clockwise. When he releases the plane, the propeller is spinning clockwise. The propeller was powered by an elastic band - releasing it would cause the propeller to spin counter-clockwise. The error was noticed in post production but couldn't be fixed without re-shooting the entire continuous one-shot or re-doing the CGI. They decided to leave it in hoping no one would notice (though they revealed the goof in the director's commentary).