Revealing mistake: When Rose and Jack first enter the boiler room, they run towards the right. If you look closely you can see the reflection of the worker in the back to the left in the mirror they use to make the bolier room look longer. In the next scene they are running in the opposite direction, because the set is so small due to the mirror, and once again you can see the same reflections caused by the mirror.
SevenThirteen
15th Jan 2008