I came out one morning and my rear left Goodyear tire was totally flat.

I changed the tire, put the spare on and drove it immediately to the Goodyear tire center.

They said that particular model of tire was defective.

They also told me at that time that my rear shocks were leaking - which is a first that I have heard of it.

I get the car completely checked with every 3000 mile oil change, etc.

Is there ANY way that the car tilting like that for an entire night could have contributed to the shocks (or other parts of the car) problems...?

If the car was not moved at all with a flat tire, about the only possibility is rim contact with the ground. The sway bars may be under tension as well, however they take much more of a pounding on a normal drive through the country side.

Unfortunately, the airbags in the shocks degrade with time, and can leak with normal age and wear. The same goes with air lines as well. It may start slowly and undetectable at first, but eventually you may notice the air leveling kicking on more and more, and eventually it may run continuously, or maybe even experience ride quality and height issues in the rear with a load once they are bad enough.

So, could the flat tire in ANY way have contributed to the leaking shocks or sway-bar or...?

Negative. Any statement to the contrary would require proof.

Several years ago, my in-laws Ford Escort wagon developed a flat overnight. This was one of those -10*F nights. Come next morning, she attempts to go to work and didn't notice the flat. When the car moved, the cold flat part of the tire got wedged into the spring of the strut and ended up ripping out half the strut.

But I agree with Randall.

Yea these guys are all correct. I had the same issue minus the flat tire. It just happens over time.