Error in PSX Final Doom level 19, Deepest Reaches:

In the PlayStation 1 version of Final Doom there is an area
of level 19 in which some mistakes were made in map design.

The flawed area is near a teleporter booth located a few
paces to the southeast of the yellow key.  The area may be
identified on the Automap by an absence of walls where some
should appear after exploration.

The PSX Final Doom maps were copied from the original PC
version of the game.  However, not all maps are completely
identical to their PC counterparts.  For example, in the
PSX game some rooms on some maps had to be vertically
shortened, and this is where the flaw occurred during map
translation.

In PC Final Doom, there's a tall elevator near the yellow
key, not a teleporter.  Most of this elevator was removed
from this PSX map, but a small, nonfunctional part of it
remains, a part of the floor that was once the back edge of
the elevator.

If you try to face towards this area and use your Activate
button, you may hear a noise as if an elevator is dropping
and rising again; but in reality no complete or functional
elevator remains there.