Detecting a mouse click on a custom 2D mesh?

I have a 2D game core where I create trails using custom meshes. I want to be able to detect a click on this customly created mesh. I tried adding a MeshCollider and used an example code I found:

     if(Input.GetMouseButtonDown(0))
     {
         var ray = Camera.main.ScreenPointToRay(Input.mousePosition);
         RaycastHit hit;

         if(Physics.Raycast(ray, out hit))
             Debug.Log("Mouse Down Hit the following object: " + hit.collider.name);
         else
             Debug.Log ("Nothing was hit!");
     }

It seems to "sort of work". I get an occasional hit from this, but the result seems really random.

Basically all I need is to see if my trail has been clicked, but at this point I'd be happy to get some insight into how I can visualize the shape the raycaster tests against.

[Update] Ok, so I found 2 issues with this:

1) The normals were only correct for half the triangles. I changed the generation algorithm so now the normals are faced towards the camera. However, now it only works for the 1st quad being drawn which takes me to issue 2:

2) The mesh collider isn't being updated despite me calling mCollider.sharedMesh = mMesh; at the end of the update. I can update it manually by clicking any of the variables in the editor, such as IsConvex to on and off and it works splendidly after that. How do I do this refresh manually through code? This is my currect mesh construction code:

 void ConstructMesh()
 {
     mMesh.Clear();

     mMesh.vertices = vertices;
     mMesh.normals = normals;
     mMesh.triangles = triangles;
     mMesh.uv = uvs;

     mMesh.RecalculateNormals();
     mMesh.RecalculateBounds();
     mMesh.Optimize ();

     mCollider.sharedMesh = mMeshFilter.sharedMesh;
 }