Originally intended as a low-budget horror movie about an evil alien. After the success of E.T. the Extra-Terrestrial, the producers made the alien into a lovable character, and added a kid who befriends it. Director Juan Piquer Simón was not satisfied with the final result.
A widely-circulated rumor that script was submitted to Steven Spielberg as a sequel to E.T. the Extra-Terrestrial is false.
Originally filmed in French and Spanish; the actors learned both languages. It premiered in France before Spain.