I have seen the movie, I also wondered how she was able to fill the whole bathroom with and only affected the Cinema beneath the bathroom and no leakages in the bathroom door.
Such a high graded facility with no security and the scientist who was a double agent.
While escaping with the merman, the shifting of camera makes me wonder why they didn't check the recordings to see who was in the room before the security breach.

It is an awesome movie, when both of them were killed at the end, the merman came back to life and took her into the waters and brought her back to life too. I wonder what happens next, if they both lived under the sea or she came back to her home. Nice movie though