Ignore the movie. Titanic did have lookouts on watch. But spotting icebergs isn't exactly that easy at night. First of all, you're maybe only seeing a quarter of an iceberg at most when you see photos of one. And typically only a 1/9 of the iceberg is above the water. The majority of the iceberg is underwater so you can easily be right on top of it and think you have yards to go before you reach it. Even during the day it's difficult to spot some of the portion that's underwater, at night it's impossible.
Then you have what an iceberg really looks like. Think it's this lovely white object that's easy to spot? Think again. What looks white during the day is filled with dirt and rubble. Up close it's not as white as it appears and at night it becomes far harder to see. You might be able to spot one at night if you have a very bright full moon and no cloud cover that night, but if you have a new moon or if there;s cloud cover you can forget it. And if the seas are calm it helps to decrease the odds of seeing an iceberg at night because you're more likely to see the motion of the waves breaking against the iceberg than you are the actual iceberg.
In addition the temperatures get cooler as you get around icebergs, making it harder to see distances with binoculars or telescopes due to fogging of the optics. You actually hear icebergs due to the popping sound before you see them at night.
The night Titanic sank was a new moon. It was reported that you could see the stars on the water, which tells us the sky was cloudless and the seas calm. But starlight doesn't provide enough light to see by, that new moon means it was a dark night making binoculars useless even if they had had any (they didn't, someone had screwed up and never placed them aboard). Cold temperatures reduced visible ranges. Lookouts Frederick Fleet and Reginald Lee would have first heard the sound of the iceberg, alerting them as to which direction to look in. It was Fleet who first sighted the ghostly image and gave the warning. Had conditions been different he might have spotted the iceberg sooner.