was there any hoax related to the sequel?
Yes, the hoverboard hoax.
Back to the Future Part II
Zemeckis said on the film's behind-the-scenes featurette that the hoverboards (flying skateboards) used in it were real, yet not released to the public, due to parental complaints regarding safety. 
who played marty in back to the future Michael J. Fox what was the premise of the film? Marty McFly, a teenager accidentally sent back in time to 1955 in a time-traveling DeLorean automobile built by his eccentric scientist friend Doctor Emmett "Doc" Brown. what kind of cultural impact did the film have? "Back to the Future" has influenced or been referenced in a variety of media, including: "American Dad". does it have any sequels? Yes, "Back to the Future Part II". does it have same character mentioned above? Yes. was it played by same actor? Yes. were any actors from the first film replaced while making the sequel? Yes, Crispin Glover. who replaced him? Jeffrey Weissman. what are the other areas of work explored by the actor who was replaced? He is a filmmaker, musician and author. what are his works as an author? "Oak-Mot" and "Rat Catching". what are his achievements as a musician? He released an album titled "The Big Problem Does Not Equal the Solution, The Solution Equals Let It Be" through Restless Records.
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Back to the Future Part II [SEP] Hoverboard hoax
Zemeckis said on the film's behind-the-scenes featurette that the hoverboards (flying skateboards) used in it were real, yet not released to the public, due to parental complaints regarding safety. Footage of "real hoverboards" was also featured in the extras of a DVD release of the trilogy. A number of people thought Zemeckis was telling the truth and requested them at toy stores. In an interview, Wilson said one of the most frequent questions he was asked was if they are real.