I did the same......had a bucket of water and cloth to immediately wipe any over-spray.I used the 303 on my car the past weekend. Application was easy. I used a piece of cardboard to protect the windows. The solution pooled on the plastic pieces like the door handles but I just wiped it away immediately. I was worried it would discolor the plastic, but a few days later there is no discoloration.
No noted issues with any discoloration or other issues.
That 303 sure makes water bead up!
Just hope it lasts....