-On the 2nd visit some of the walls seem to be moving, or pulsating.
-There are some posters that say "Havoc Business Daily", same as the ones in SH3's subway.

Prison

-Sometimes when your in one of the rooms you can hear footsteps and a shadow passes by the little hole/window.
-In the cells Henry's head is below the window/holes, but in the center rooms Henry is easily able to see threw them.

Building World

-This area seems to be made up of random areas, much like nowhere (SH1) and the church (SH3).
-On the second visit, if you go in the clock room before solving the puzzle, Henry will be upside down.
-The 1st time you get there, at the first area, if you look up you can see the gum head enemies jumping across the buildings.

Hospital

-In the 2nd floor room with the wheelchair, you can see a shadow moving up and down on it.

Apartment Building

-During the 2nd time there, when you have to find the bodies to unlock room 105, the bodies are actually Walter (the hair makes it obvious, even if you can't see the face).
-During the 2nd time there, in the room that had all the children in it, if you look in the crib there is a baby in it, which wasn't there the 1st time through.
-The first time you go into room 207, Walter can be seen pointing out the window (the same way he did when you looked out the window, and when young Walter did it at the end of the building world).

Stairway

-There are elevators going up and down outside of the stairway.
-In one of the rooms outside of the stairway there is a baby by a door.
-In one of the rooms outside of the stairway there is what appears to be a sheep.
-When you get to the bottom, outside of the fence is what appears to be a bunch of giant heads in a giant crib.

Random

-The baby monsters (victims 7&8) say "Reciever of wisdom" when they point at you.
-If you kill a sniffer and leave the other sniffers alone they'll eat the dead one.