Detecting that I'm clicking a unit even though I'm not?

I'm working on a Turn Based Strategy game and have an issue.

Here is what the game looks like right now with 2 enemy units and one of my own units that I bought from the base (currently the purple sphere. Yay placeholders!) http://i.imgur.com/SiDyfdG.png

In my script, during Update, I call this segment of code:

 //if player left clicks on a unit
 if (Input.GetMouseButtonDown(0)
     && Physics.Raycast(ray, out hit, 500f, gameControl.getUnitLayer()))
 {
     Debug.DrawRay(ray.origin, ray.direction, Color.white, 100f);
     selectUnit(hit.collider.gameObject);
 }

Now here is the exact same scene shown above, but with the camera only showing layer 11, "Units" http://i.imgur.com/zUqcDAE.png

Yet the code segment is running every time I click the mouse, even if I'm very obviously not hitting anything on the units layer.. Here's a picture in the scene view of some of the draw rays, clearly not hiting any of the 3 units: http://i.imgur.com/DNJR3AV.png

Lastly, in other areas of the code, I have the information as follows. The values ARE NEVER CHANGED.

 Ray ray = mainCam.ScreenPointToRay(Input.mousePosition);
 private const int unitsLayer = 1 << 11;

And that's all the information. So why is it detecting the raycast every time I click the mouse, even if I'm not clicking on a unit???