Contrast Montage: At the start of the film, we see an upper-class English lady and her entourage, a middle-class newlywed couple and some Irish emmigrants preparing for their voyage.
The Determinator: Captain Rostron of the Carpathia, who tries to reach the Titanic before it sinks with no regard to the hazards facing his own ship. The fact that he fails to reach Titanic in time doesn't diminish the Crowning Moment of Awesome in the least.
Dirty Coward: J. Bruce Ismay is depicted in this fashion when he scurries into a lifeboat at first opportunity. It's one of the movie's few Critical Research Failures (albeit one justified by the time), since contemporary reports indicate that Ismay, far from being a coward, strenuously worked hard to get people into the boats, helped launch them and only took a seat in one of the last boats to leave the ship having made sure that there were no women and children nearby.
Massively debatable as he is often shown in the film helping, or at least trying to help, with the launch of the boats and getting the survivors into them. He only gets into the boats when there is no-one left to go on the side he was on, with First Officer Murdoch on the Starboard side, where he actually asks "Is there no-one else?" regarding a boat that was only leaving half-full (of which there were many on the actual sinking).
Distress Call: The Californian ignores the SOS, but the Carpathia's radio operator is on the ball, gets to his equally diligent captain and the ship turns around to race to the Titanic.
Enforced Method Acting: As there were no water tanks in studios big enough to accommodate the sets, outdoor scenes were shot in an open-air swimming pool. In November; none of the actors wanted to have to jump in. Kenneth Moore wrote:
"I would have to set an example. I leaped. Never have I experienced such cold in all my life. It was like jumping into a deep freeze just like the people did on the actual Titanic. The shock of the cold water forced the breath out of my lungs. My heart seemed to stop beating. I felt crushed, unable to think. I had rigor mortis... without the mortis. And then I surfaced, spat out the dirty water and, gasping for breath, found my voice. 'Stop!' I shouted. 'Don't listen to me! It's bloody awful! Stay where you are!' But it was too late as the extras followed suit."
For Want of a Nail: The appalling death toll could have been prevented if lifeboats were provisioned on the basis of passengers and if ships had to maintain a 24 hour radio watch - a ship big enough to hold hundreds of people was visible on the horizon but had turned their radio off.
Then again, it was the Titanic's sinking that enabled those safety features to be codified in the first place. Had she not sunk, these features wouldn't have been added (or they wouldn't have been implemented as quickly) and there likely would have just been a worse sinking later.
On top of that, the radio operators were in the employ of Marconi, not the ship itself. Hence the priority was in relaying paid personal messages rather than weather reports.
Heroic Sacrifice: We're shown several scenes where crewmen die trying to keep the ship afloat and operational for as long as is humanly possible. Several passengers are shown giving up their places in lifeboats so others may have them.
Historical Hero Upgrade: While there's no fair way to deny most of the crew and officers acted heroically (no matter what The Other Movie depicted) and while if even half Lightoller's autobiography is true the man was a certifiable hero, the movie takes it just a bit too far, showing him launching lifeboats he had nothing to do with and in places he couldn't have been.
History Marches On: Titanic is shown going down in one piece. Since the discovery of the wreck in 1985, it's generally accepted that the ship broke in two before it sank.
Homage: Several scenes from this film were remade/reworked in Titanic; most notably, just after the ship goes down we see a brief shot of a young man and a young woman struggling to both climb on top of a floating box.
Infant Immortality: Averted, naturally; most poignantly with the waiter who takes a young boy who's lost his mother under his wing, stops him from being crushed by the crowd... only for them to both drown minutes later.
In a later scene (that gets cut for broadcast more often than not), a crew member (possibly the above-mentioned waiter) makes it to the overturned Collapsible B with a child in his arms. With the last of his strength he gives the infant to Lightoller, pleading with him to take care of the child. Lightoller takes one look inside the child's hood, realises it's dead and sets it adrift in the ocean.
It's actually two of the Irish steerage passengers who swim up with the child. The two of them survive after being pulled on board; but the child didn't, despite their heroic effort to save it.
Shown Their Work: It's universally acclaimed at being not only a completely realistic portrayal of the disaster itself but also of the social/class structure of the time.
Spot of Tea: After the engineers are told to stay below decks to keep the lights running as long as humanly possible and that a rescue ship would be there Real Soon Now - ridding them of any chance to get to the surface where they might survive - we get this resigned response;
"Let's hope they're right, boys. If any of you feel like praying, you'd better go ahead. The rest of you can join me for a cup of tea."
Absolutely personified by Robbie Lucas. After figuring out early on that the ship is going to sink and that there aren't enough lifeboats for all the women and children, let alone the men, he packs his wife, two daughters and a son onto a boat and bids them farewell without doing anything more extreme than raising his voice slightly... once. All so they won't be panicked, although his wife twigs what's up when she sees him nearlybreak into tears after telling his son to look after her mother. It's heartbreaking to watch.
Stock Footage: Scattered throughout the film. The christening is a Stock Footage clip (the real Titanic didn't have one). Most interestingly, four clips—two shots of the ship sailing in calm waters, and two shots of a flooding engine room walkway—were recycled from the 1943 Nazi propaganda Titanic film.
Survivor Guilt: Most demonstrably in Ismay's face as he watches the boat go down from the safety of the lifeboat he sneaked onto.
Take That: One of the taglines of the film was 'The Real Story of the RMS Titanic', a jab at the less-than accurate 1953 Titanic film.
Tempting Fate: Famously, the ship was branded "unsinkable"... by the press, and the public went along with the hype. Averted with Andrews, the ships' head designer.
Captain Smith: But... she can't sink. She's unsinkable!
Andrews: She can't float.
Thousand Yard Stare: A steward finds Andrews alone just before the sinking and asks, "Aren't you even going to make a try for it, sir?" Andrews shoots him an absolutely terrifying one of these.
Most of the survivors at the Monday morning memorial held aboard Carpathia have haunted, blank expressions, except for the few who are quietly sobbing.
Throw It In: The ominous creaking noises the ship makes as it founders were actually made by the set as it was tilted into position.
Understatement: Several occasions, see also Gallows Humour and Stiff Upper Lip above. From Lucas, who's fully aware he only has a couple of hours to live but is trying to convince his wife to get into the boats with their children without worrying her:
"It's very tiresome. We've struck an iceberg and damaged the ship. We may be a day late getting into New York."