Assets/Scripts/Enemy.cs(61,44): error CS1955: The member `UnityEngine.GameObject.tag' cannot be used as method or delegate

i’m just stuck… here’s my code

enter code hereusing UnityEngine;
using System.Collections;

public class Enemy : MonoBehaviour 
{

	static bool go_left = false;
	private int timer = 300;
	private int rand_num;
	static int num_chosen;
	public GameObject Enemy_bullet;
	public float speed;

	void Start()
	{

	}
	
	// Update is called once per frame
	void Update () 
	{
		if(go_left)
			transform.position = transform.position + new Vector3 (-.25f, 0, 0);
		else
			transform.position = transform.position + new Vector3 (.25f, 0, 0);

		timer -=1;

		if (timer <2)
		{
			rand_num = Random.Range(0, 20);
			num_chosen = rand_num;

			if (num_chosen == 2)
			{
				Instantiate(Enemy_bullet, transform.position, transform.rotation);
				Vector3 newPosition = transform.position;
				newPosition.y -= speed * Time.deltaTime;
				transform.position = newPosition;
			}
			timer = 300;
		}
	}

	void OnTriggerEnter(Collider col)
	{
		if(col.gameObject.name == "Left_Wall")
		{
			go_left = false;
			MoveDown();
		}
		else if (col.gameObject.name == "Right_Wall")
		{
			go_left = true;
			MoveDown();
		}
	}
	void MoveDown()
	{
		string[] enemies = new string[1] {"aliens"};
		string aliens = GameObject.FindGameObjectsWithTag("Enemy");
		foreach (var entity in enemies)
			transform.position = transform.position + new Vector3 (0, -.5f, 0);
	}
}

GameObject.FindGameObjectsWithTag() returns an array of GameObjects. So the line should read:

 GameObject[] aliens = GameObject.FindGameObjectsWithTag("Enemy");

‘aliens’ is local, and you are not currently using it, so I’m not sure of the intent of this particular line of code.

P.S. The error you list is not what I would expect from this code, though the line is clearly wrong. Are you sure this exact code generated that error?