Poisonous Valley seems to take place in a valley, just with Poisonous Liquid (Acid) everywhere. There are occasional stone tunnels and stone rocks protruding from the poison. There is an overall brownish theme with the modeling, and the model work is intricately shaped but in-textured aside from the acid wall that starts in the corner and makes its way through. Many players consider this map as a Normal Map due to the fact that falling will likely kill the player.
When the map was first added to the game it shared the same OST as Mysterium. This was changed with the June 2018 update.
This map is the first easy map to be added since very soon after Flood Escape 2 was released.
This map is the second to have its own unique acid type. The first was Dark Sci-Forest, being purple.
There is a cauldron near the end of the map with the meme "You know I had to do it to em". The liquid in the cauldron also acts as acid. This is the third appearance of the meme in the game, proceeding Sinking Ship. If you go inside the cauldron you can drown.
This map has a poisonous wall, making sure there are no people alive by the end of the map. This is the 2nd to do so, after Graveyard Cliffside.
The wooden house at the end shows a striking resemblance to the wooden house at the end of Gloomy Manor.
NBC (No Buttons Challenge) is possible on this map. Right after you teleport to the map, quickly press the "Low Detail Mode" button then everything in EventString will stop, except water and change state of it. This concludes that things that are controlled by buttons will stop too. This is due to a precise glitch at the exact right moment would make everything go 5-6 studs up. However, this is no longer possible since the End Zone only opens when all buttons are pressed.
Before the poison rises, you will see the crates moving like floating objects even though there is no poison (liquid form) below it.
There are two secret rooms in this map, one is located behind the poison falls, near the second button, the other is located in the middle of the river.
There is more than just a secret. At the right side of the secret room in this map, you will see a NonColliding FE1 Guide pouring Acid on the water fall. This is the reason why the water turned into acid. You can also see a book with an image of Flood Sword on the cover of it and the very point of the Flood Sword. This concludes that the Flood Sword is broken. This was first discovered by NumerousLjbustria (Jasperical) and made public by Gentleberry16 Gerek.
If you Shift-Lock into the wall at the third button, you will see a grey wall that some people say is a wall-jump.
When you swim in the rising poison and the poison wall at the same time, the rate of air loss will be doubled.
There's a chance you will be spawned on the platform where the first button is located.
The ID of this map had changed due to poisonous valley changing into a new map made by GustForce with another wall just like the one on this map and Graveyard Cliffside.