Door object array

You shouldn't do that like this! You should use a fairly advanced but simple concept called an interface!

It works like this: You raycast (like you have done) forwards, but instead of checking the tag you should get every single script on this object. Do that like this:

 foreach(var script in hit.gameObject.GetComponents<MonoBehaviour>()) {
     //Do something to every script attached to hit object
 }

Now you need to check if this is indeed a door. But first we need to decide what is a door and not. Create two new scripts. One called Door and one called IDoor. IDoor should be an interface. An interface should contain any variables that are required for a door. Long story short, write this in your IDoor:

 public interface IDoor { //Replace the "class" with interface and remove the " : MonoBehaviour"
     void ChangeDoorState(); //Any script 'implementing' this interface MUST contain this function!
 }

And then write something like this for your door: public class Door : MonoBehaviour, IDoor { //You need to implement the IDoor interface by adding , IDoor behind MonoBehaviour!

     public void IDoor.ChangeDoorState() {  //Since Door implements IDoor: Door must have a void called ChangeDoorState that is public!
         //If door is closed, open
         //Else, close
     }
 }

Why you should do this might not seem very clear right now, but what you now can do inside your raycast and foreach statement is this:

 foreach(var script in hit.gameObject.GetComponents<MonoBehaviour>()) {
     //Do this for every script attached to hit.gameObject
     if(script is IDoor) { //If the script were checking implements IDoor
         (script as IDoor).ChangeDoorState(); //Since it is an IDoor, we know it must have a function called ChangeDoorState!
     }
 }

I havent tested this code, but as long as you attach the door script to a door this should work very nicely!

  #pragma strict
  
  private var isOpen : boolean = false;
  
  var doorOpenSound : AudioClip;
  var doorCloseSound : AudioClip;
 
  var rayLenght = 10;
 
  function Update(){
  
   var hit : RaycastHit;
   var fwd = transform.TransformDirection(Vector3.forward);
     if(Input.GetButtonDown("Interaction") && isOpen == false){
         if(Physics.Raycast(transform.position, fwd, hit, rayLenght)){
             if(hit.collider.gameObject.tag == "DoorDefault"){
                  hit.collider.GetComponent<Animation>().Play("door_wood_open");
     
                 audio.PlayOneShot(doorOpenSound[Random.Range (0, doorOpenSound.length)]);
                 audio.Play();
                   isOpen = true;
             }
         }
     }else if(Input.GetButtonDown("Interaction") && isOpen == false){
         if(Physics.Raycast(transform.position, fwd, hit, rayLenght)){
             if(hit.collider.gameObject.tag == "DoorDefault"){
             hit.collider.GetComponent<Animation>().Play("door_wood_close");
     
                 audio.PlayOneShot(doorCloseSound[Random.Range (0, doorCloseSound.length)]);
                 audio.Play();
                   isOpen = false;
             }
         }
     }
 }