Can't identify where this lip is in hiding in this model This is somewhat related to my previous question here, however this question is related to the partial invisibility of one of the sides when exported and loaded into ThreeJS. 

In there it looks like this:

Notice the pink lip at the top of this side. In Blender I've extended the red side to the top of the bag so it should cover whatever this pink lip is - the problem is I don't know where it's coming from. 

Based on the "Edit Mode" view there are only two sides here, both are the same height and width &amp; both are facing the same direction (outside). I've also recalculated the normals after I flipped the directions but I still see this pink lip. Why?

Here's the Blender view with the two sides hidden:



Any advice on this would be good.

P.S. It has also been suggested that this can be caused by not using a THREE.DoubleSide but I am using that as the material so this shouldn't be the issue:

EDIT 
Link to the uploaded bag:
Probably not (yet) an answer, but at least I can show something that seems weird in your model:





You have some different faces for interior and exterior sides of your bag, but their normals are all directed outwards, instead of being as usual, ie: I expected the exterior face normal pointing outside, and the interior face normal pointing inside the bag.

It seems there are many face normals set like this, it seems a bit weird imho.

I will try to learn Threejs basic concepts to experiment (never used before, but interesting) but I would try before making this mesh look better in Blender before...

edit: imho, this mesh has many problems (many of them clearly found by the 3d print addon mesh checker, or the mesh analysis tool, btw) which can confuse an external engine: face distortion (non planar) face overlaps, and others...