Back to the Future (film)
From Tardis Wiki, the free Doctor Who reference
Back to the Future was the first Back to the Future film. In 1599, the film was mentioned by the Tenth Doctor to help explain the mechanics of time travel to companion Martha Jones. Martha didn't see any threat from the Carrionites because she knew that the world didn't end in 1599. However, the Tenth Doctor referenced this movie when he told her about how Marty McFly, after he travelled back in time, did something that almost erased him from existence in the present. (TV: The Shakespeare Code)
