A Kid in King Arthur's Court(1995)

Calvin Fuller is about to break curfew...by 1500 years.

A Southern California kid named Calvin Fuller is magically transported to the medieval kingdom of Camelot through a crack in the ground caused by an earthquake. Once there, he learns he was summoned by the wizard Merlin, who needs Calvin to save Camelot. Using dazzling modern inventions, can Calvin help King Arthur retain his crown and thwart the evil Lord Belasco?