There is only one enemy in this level, and its the boss, Hans Grösse.
Unlike the original game he is not hidden behind door at the end if the large hall room. He is waiting for you right at the end of the large hall just before the door.
The secret area exists just the same as in the original, and has a Heavy machinegun. Hans is very weak to this weapon, and dies quickly.
Instead of leaving out into a field as in the original, the exit opens up into a vista of the German Alps, with birds flying by, to indicate the new location of Castle Wolfenstein (and to tie it into B.J.'s memories of the place).