 In promotional material such as  _Back to the Future Part II Featurette: A Behind the Scenes Look (1989) (TV)_ (qv)  director, Robert Zemeckis (qv) explained that "hoverboards float  on magnetic energy". He also added, "theyve been around for years,  its just that parent groups havent let toy manufacturers make  them. But we got our hands on some and put them in the movie." He  was only joking of course but interesting enough, Mattel (whose logo  appeared on the hoverboard props) soon found themselves overwhelmed  with callers asking where they could buy one. Although they looked  pretty convincing in the movie, the hoverboards were simply wooden  props attached to the actors feet. To make the boards fly, the  actors were suspended by cables.