What are some secret places here?

Hint 1 of 13:

There are only two secret places, and both involve finding the Control Room
of the Enterprise.

Hint 2 of 13:

(1) Near the end of the level, go up the escalators.

Hint 3 of 13:

In that big, central section, you'll find the entrance in there.

Hint 4 of 13:

Look for a hidden switch.