Say what you like about the science behind Titanic's ending - it had a huge emotional impact and damn it, it worked. It worked.
Still, almost twenty years on, James Cameron is still salty about the ending being mercilessly picked apart with reason, logic and facts. In fact, Cameron singled out none other than Mythbusters's fact-checking of the ending of Titanic in a recent interview with Daily Beast.
Going by his reaction, it seems like Cameron worked this out and is having none of Mythbusters' shit. "You’re Jack, you’re in water that’s 28 degrees, your brain is starting to get hypothermia." That make sense so far. Sure. Continue with your reasoning, James Cameron.
"Mythbusters asks you to now go take off your life vest, take hers off, swim underneath this thing, attach it in some way that it won’t just wash out two minutes later - which means you’re underwater tying this thing on in 28-degree water, and that’s going to take you 5-to-10 minutes, so by the time you come back up you’re already dead. So that wouldn’t work. His best choice was to keep his upper body out of the water and hope to get pulled out by a boat or something before he died."
Cameron actually helped out with that particular episode of Mythbusters, in which the ending of Titanic was explored, and added that "(they're) fun guys and I loved doing that show with them, but they’re full of sh–."
So, even with all that, you're still going to get people sharing that meme of the outline of the board. James Cameron says for you to shut your mouth.