I've always wondered, why do Fords appear the most in movies, Epecially TV movies? GM is second most shown, and Chrysler is the third.

Because they are the most common cars on the road.

As Ford is widespreak in USA for all types of vehicles (cars, busses, trucks, etc.) and all over the world for cars (even if they are not the same cars, they are sold under the same brand), it is normal that there are lots of them too.

Because Fords are inexpensive with all the negative media exposure they get.