After McQueen fixes the road and everybody is cruisin up and down remembering the old days, Lightning and Sally pull up to the intersection where Sheriff stops them while the tractors go by, nodding up to show the light now works and they had a red light. Well you can clearly see JUST before they got there the light was still blinking yellow as it always had been. Technically you could argue and say it is possible, which it is, however I don't think that was intentional. Your call.