Two out of my four tires have different tread on them.

I heard this is deadly for an AWD car.

I've been running on all different tires. When I got my car inspected at the dealer I asked them if it will harm anything but they didn't seem concerned about it and told be that it shouldn't do anything.

I don't trust dealers and I'm wondering with specifically the G, what components could this damage if I am running it on tires with different tread?

I have an appointment to get all four new tires on Saturday but I am concerned with the damage I could have done already.

 

As long as they were fairly close to the same rolling diameter (i.e. within a few percent), you should be just fine. If you were running tires with 10% difference in diameter, you might damage your transfer case, but if they're the same diameter, but with just a different tread design, I wouldn't worry one bit.

 

You are probably close enough that no harm was done. Your AWD light will come on when there is a problem.
The front to rear diameter variance has to be much tighter for AWD. There's been issues at speeds over 75 mph when the variance is over 1%.
Here's a list of staggered combos in popular sizes that will work as long as you have proper width wheels to mount them on, the percentage in parenthesis is the amount of variance. A positive number is better (this means the rear tire is larger diameter) since the rears wear faster this variance will get closer to zero over time. The combos with the rear tire already smaller (negative number) the variance will get worse over time.

18s
235/45 & 265/40 (0.07%)
245/45 & 275/40 -0.07%
255/45 & 285/40 -0.22%

19s
235/40 & 265/35 -0.37%
235/40 & 275/35 0.67%
245/40 & 275/35 -0.52%
245/40 & 28535 0.51%

20s
235/35 & 275/30 0.07%
245/35 & 285/30 -0.07%

This calculator should be used when trying new setups~
http://www.myg37.com/forums/tire_rim_calculator.php