At one point a character sneaks through the bowels of the ship from one end to the other. This would be hard to do since he would have to pass through the lower level reactor compartment. Even if you could do this (there is no such passage on any nuclear sub) it would not be very healthy.
I just saw the movie Crash Dive 2 (which is also about submarines and also involves an enemy Akula-class sub) and it has many recycled scenes from Crimson Tide. To name a few: the scene where the sub does a "snap shot" of two torpedoes, the scene of the Akula being hit, and the scene where a torpedo barely misses the heroes' sub.