They Had Enough Lifeboats
The movie makes it appear as if the disaster took place because they didn’t put enough lifeboats on the sides of the ship. However, they technically did have enough lifeboats. Not enough to save everyone who was on board, of course, but they did have enough to achieve the legal minimum, so technically those in charge weren’t to blame for that.
Why was it legal to have less lifeboats than necessary to rescue all passengers? That’s a different question altogether.