Radiator

My car had been running great until a couple of days ago. It all of a sudden started getting hot. I was close to home so I made in home. When it cooled off I checked it out and here is what I found; first of all I might add it was like 107°outside when I was driving home. Anyway I checked my oil filter and it was loose, I was able to turn it with my hand and also at the top of the radiator along the seam it is cracked which I am assuming is where I lost my water causing it to over heat. My question is, this does not necessarily mean it blew a head gasket right? Could it be that the thermostat is stuck?