6 Kate Winslet flashed Leonardo DiCaprio on the first day (of their meeting) so that there would be no awkwardness between them during the filming of the nude scene.

The nude scene was the first meeting between the two actors. So, to break the ice, Kate simply decided to flash her nude body to Leonardo DiCaprio which made them laugh. Thus, there was no incipient awkwardness or tension when Jack was painting Rose in the buff.(source)

7 The scenes set in 1912 lasts for two hours and thirty minutes, the exact time it took for RMS Titanic to sink.

The scenes set in 1912, i.e. the whole movie except the present-day scenes and the opening and ending credits, have a total length of two hours and forty minutes, the exact time it took for Titanic to sink. Also, the collision with the iceberg reportedly lasted 37 seconds, which is how long the collision scene is in the movie.(source)

8 Everyone (trade circles) including James Cameron thought that Titanic made on a budget of 200 million USD would end up as a catastrophic disaster instead, it went on to get an initial worldwide gross of 1.8 billion USD 

Before the film release various film critics and insiders thought that Titanic would prove to be a “big disappointment” at the box office, Cameron shared this pessimism . But to their surprise Titanic went on to become a blockbuster initially grossing more than 1.8 billion USD worldwide. In fact, it was the first movie to touch the billion dollar mark.(source)

9 James Cameron, who was deeply fascinated with shipwrecks considered the RMS Titanic as “Mount Everest of Shipwrecks” wrote a script for Titanic and sought Hollywood funding to get to dive to the shipwreck; not because he particularly wanted to make the movie.

Jack Cameron had a strong fascination for shipwrecks and considered RMS Titanic as the “Mount Everest of Shipwrecks.” Once he saw an IMAX movie made from the footage of the wreck itself, his fascination getting stronger, he thought of getting Hollywood to fund his passion for his underwater diving (to seek and film RMS Titanic) and the only way was to make a film on the Titanic. Thus, the movie Titanic was born!(source)

10 The character in Titanic who fortifies himself with alcohol and rides down the ship into the ocean along with Rose and Jack is based on the real-life person Chief Baker Charles Joughin. He survived the ordeal and credited the booze for that.

The real Charles Joughin may very well have been the last survivor to leave the Titanic. Joughin rode down the Titanic and landed in the ocean. He kept himself afloat by paddling in the water for almost two hours. Joughin who had consumed copious amount of alcohol said that he did not feel the cold while in the water (probably the whiskey kept him warm). Joughin was rescued by RMS Carpathia in the morning with only swollen feet as a reminder of his two-hour paddling.(source)