UnityEvent Array coding C#

To complete my comment:

1. If a public variable isn't initialized it will once you create an instance of the component in the editor. So basically the array will be instantiated, but the length is zero. Unity does the same for Lists.

2. The array is most likely used in conjunction with a for loop. If your array is of length 0, the for loop exits before it even enters the loop body.

The following is completely valid:

public class Test : MonoBehaviour {

public int[] myArray; // On adding this component myArray gets initialized 

// Update is called once per frame

void Update () {

    //myArray.Length is zero, so the Debug.Log is never run

    for(int i = 0; i < myArray.Length; i++){
        Debug.Log(myArray[i]);
    }
  }
}