If left to dry, it would leave marks (smears, spray pattern, etc, but nothing permanent), but if you were to use another (light) spritz or even a moist cloth, followed by a dry one, you could wipe it off. S+W is water based, so you wouldn't need to use solvents to remove it (Unlike some other waterless washes).
S+W isn't a "wash and wax" type product, so it doesn't require time to dry on the surface first. You just spray it on, let it "work" for a few seconds, then wipe it off.
If you use too much, you may get some streaks, depending on how well you buff, the absorbancy of the towel, etc. but it's not like you'll permanently damage the glass or paint.
Hope this helps!