All the Virginia license plates shown on car is a series of just numbers. However, all non-personalized Virginia license plates have three letters, a hyphen, and then four numbers.
Carrie's mother's wagon bears Missouri license plates. Missouri plates are 6 characters, not 7. Also, Missouri plates on a vehicle usually start with two letters. The plates are also missing Missouri tags, etc. It appears the plates were printed on a laser printer and glued to real plates (no screw holes visible at all).