From the documentation for reverse:

Used without arguments in scalar context, reverse() reverses $_.

That is, $_ is only "special" to reverse when:

• reverse is called with no arguments; and
• reverse is called in scalar context.

In the case of print reverse;, it is not in scalar context, so $_ is not special. You're calling reverse with the empty list as an argument. It reverses that list and return the result (which is still the empty list).