20 Things You Somehow Missed In Back To The Future
15. The First Scene Tells You How The Movie Is Going To End
After Marty uses the DeLorean to travel to 1955, he tracks down Doc to find a way to return to his timeline. Doc believes the only power source that could allow the DeLorean to time-travel is a bolt of lightning. Luckily, Marty knows the exact day and time the town's clocktower will be struck by lightning.
In the climax, Doc climbs the clocktower to secure the power line so the lightning's energy will filter into the DeLorean. Cinephiles will recognise the shot of Doc dangling from the building as a homage to the 1923 comedy, Safety Last, where silent-era star, Harry Lloyd, performed the same stunt. (Before you ask, no, Christopher Lloyd and Harold Lloyd aren't related.)
But there is another Easter egg some viewers missed. In the opening credits, the camera moves around Doc's office, showcasing his array of clocks. On one of the tables, there is a miniature of the clock-face from Safety Last with Harold Lloyd hanging on the clock's hands. First-time viewers won't notice it but after a second viewing, you will realise the opening shot spells out the conclusion for the film.