FWIW, Those two lines are present on the 4K Dolby ATMOS stream via iTunes. Both audibly and in CC. Well, the first line is "Now, Let's Go!" then "Let's Go, Rose!"
I just checked it today. Perhaps the lines were missing earlier and Disney/Paramount fixed the digital streaming version...
We watched the iTunes digital last night. It's a gorgeous transfer, start to finish. The lively surround sound creaking and groaning of the ship during the sinking had our cat doing double-takes in all directions. Her head and ears got quite the workout. :)
I've decided to cancel the 4K...
Depending on when the digital code was redeemed, your existing iTunes version of Titanic may have been upgraded to 4K Dolby Vision. I redeemed my digital code back in 2012, when the Blu-ray I own was released. My digital copy in iTunes was NOT upgraded to 4K. But people who purchased the...