Implicit Downcast on array object and clearing array

 #pragma strict
 
 var selectedUnit : Transform;
 var tileSelected : Transform;
 var getSpaces = new Array();
 
 function Start()
 {
     
 }
 
 function Update()
 {
     GetMovementTiles();
     if(Input.GetMouseButtonDown(0))
     {
         print(getSpaces);
         if(selectedUnit != null)
         {
             for(var i = 0; i <= getSpaces.length; i++)
             {
                 var clearColor : Transform = getSpaces[i];
                 clearColor.renderer.material.color = Color.green;
             }
             selectedUnit = null;
         }
         
         var ray : Ray = Camera.main.ScreenPointToRay(Input.mousePosition);
         var hit : RaycastHit;
         
         if(Physics.Raycast(ray, hit, 1000) && hit.transform.tag == "Player 1")
         {
             selectedUnit = hit.transform;
             print(selectedUnit);
         }
         print(tileSelected);
         
         /*if(Physics.Raycast(ray, hit, 1000) && hit.transform.tag == "Terrain" && selectedUnit != null)
         {
             tileSelected = hit.transform;
             print(tileSelected);    
         }*/
     }
 }
 
 function GetMovementTiles()
 {
     var ray : Ray = Camera.main.ScreenPointToRay(Input.mousePosition);
     var hit : RaycastHit;
     
     while(selectedUnit != null)
     {
         if(Physics.Raycast(ray, hit, 1000))
         {
             var coordTest : Transform = hit.transform;
             for(var i = 0; i < getSpaces.length; i++)
             if(getSpaces[i] == coordTest)
             {
                 //for(var j = getSpaces.length; j >= getSpaces.
                 return;
             }
             getSpaces.Add(coordTest);
             coordTest.renderer.material.color = Color.red;
             return;
         }
         return;
     }
 }

So in this code I am trying to do two things that aren't working, #1, take an index of the array, change the material color of the object at that instance of the array to green in the first for statement. I'm getting a Warning about a downcast from object to transform @ line 22 when I leave it as it is

In the GetMovementTiles function at the bottom, I can't seem to set it so it only adds Transforms that are tagged with "Terrain", without freezing unity or breaking the function. Where would I add this to make it work?