Can the door to this area really not be opened from this direction in Tomb of Horrors?

Question

I am reading Tales from the Yawning Portal, specifically the Tomb of Horrors. There seems to be an error in the following description (emphasis mine):

24. Adamantine Door
The tunnel from the south emerges into a corridor that then heads east. The door at the end is a great block of adamantine. It has permanent antimagic effects on it, and there is no magical or physical way of forcing entry.
There are three slots in the door at about waist height. If sword blades are shoved simultaneously into all the slots, the 1-foot-thick door will swing open. Five rounds later the door slams shut. There is no way of opening it from the west side.

The way this area reads I think it should say:

east instead of west, as the intent seems to be to trap the characters in the room

This is because

They come from the corridor on the west side. Open the door. Go through the door into the room. The door closes. They are trapped inside the room. They want to get out, so they have to turn around and go west. That means they are on the east side and come from the east. If they were supposed to be trapped the description should therefore say "There is no way of opening it from the east side." as east is the side with the room. Currently it says west and that doesn't make any sense, as the characters at this point are on the east side (or they decided to keep standing around half a minute, in which case they could never again enter the room). If the current formulation is correct then it looks like there is a description missing about how the door could be opened from the east side that is the inside of the room.

Furthermore there are not a whole lot of other entries to the area behind this one.

The doors that are described in area 31 don't even exist if someone comes from the west or east. The characters would have to come from the north to make these doors exist.

Am I overlooking something or is there a mistake in the book?

I'd prefer information about D&D 5e, but I'd be interested in information from other editions, too, as the adventure was originally written in 1978 for the AD&D according to the information box in Tales from the Yawning Portal.

Answer 1

That door in the Tomb of Horrors has often traditionally been one-way as the question speculates it likely should be, although exact details of that door vary by edition.

Advanced Dungeons and Dragons

Tomb of Horrors (1978) says this about that door:

Adamantite Door: Although it is marked secret, it is very evident; the marking is simply to make certain that its actual nature is known. It has permanent anti-magics on it, and there is no magical or physical way of forcing entry. There are 3 slots in the door at about waist height. If 3 sword blades are shoved simultaneously into the slots, the 1' thick panel will swing open. This is a one way door which cannot be prevented from closing in 5 rounds! (7)

(Changes from all caps to boldface mine.)

Advanced Dungeons and Dragons, 2nd Edition

Return to the Tomb of Horrors (1998) includes this:

During Return to the Tomb of Horrors the PCs venture into the adnd Tomb, a facsimile of which is included with the Return box set. The adventure expects the adnd-2e DM to update the original Tomb to the new edition; Return to the Tomb of Horrors—the adventure proper rather than its ancillary books—has more details on page 55, none changing this door.

Tomb of Horrors was not to my knowledge otherwise updated for this edition.

Dungeons and Dragons 3.5

Tomb of Horrors (2005) says that at the end of that corridor the adventurers see this:

A door forged of gleaming metallic alloy with massive reinforced hinges bars passage beyond this point. Three vertical slots mar the door’s surface at waist height. Each slot is about 1 inch wide and 3 inches long.

That's followed by information for the Dungeon Master:

The 1-foot-thick steel door (it’s too expensive for the demons to keep replacing adamantine doors) is suffused with a globe of invulnerability effect. (However, only the door, its hinges, and the stone around the hinges are so affected, allowing it to shed any spell of 4th or lesser level.) The effect cannot be brought down by a targeted dispel magic, but it can be suppressed for 1d4 rounds if the dispel check beats a DC of 22. If the door is removed from the stone that moors it through some determined engineering, it loses all magical abilities. The door is locked (DC 45 Open Lock check), but opens of its own accord if three sword blades are simultaneously shoved into the slots.

(Links mine.) Then follows another note for the Dungeon Master:

Once open, the door automatically swings closed 5 rounds later. In addition to the invulnerability effect, the door enjoys a magical hardness (which can be suppressed for 1d4 rounds as the invulnerability effect) that allows it to mash any metal less deformable than adamantine that someone may put in place to hold it open. A character trying to hold it open needs to make a DC 30 Strength check each round to hold it open. From inside (room 25), no slots or other obvious methods can get the door open again. (25)

I've not read the Greyhawk Classics novelization Tomb of Horrors (2002) that was released during the Dungeons and Dragons, 3rd Edition era, so I don't know if this door is described differently therein.

Dungeons and Dragons, 4th Edition

Tomb of Horrors (2010) says this about that door:

Nothing! Building as it does on the 2nd Edition adventure Return to the Tomb of Horrors, the original tomb's layout is duplicated, but time has seen its guardians replaced and many of its traps defeated. Although the included map does designate the door as secret, sadly no special features of it are described. (See Tomb of Horrors on pages 100 and 154–5 for the scant details.)

Wikipedia's Tomb of Horrors entry says that a more direct port of the original adventure exists for 4th Edition, calling it an "update of the original module for 4th Edition rules, [that was] written by Scott Fitzgerald Gray and [that was] released to members of the RPGA as part of the DM Rewards program." I don't have access to this adventure.

Dungeons and Dragons, 5th Edition

As a more-or-less direct port of the original, this reader agrees that the text is likely in error and that the door should prevent those who pass through it from returning whence they came.

Answer 2

It is most certainly a mistake. It details the process by which you can enter the door on the west side, and then tells you that there is no way of doing so.