When Gaybee arrives at the police station, the inside rear view mirror is seen in the 1957 Chevrolet station wagon. When she leaves with John Frank, the mirror is still present. But when John crawls over the seat to sit in the back, the inside rear view mirror is missing.
When Gaybee is driving away from the first town and John is crawling into the back to sleep, it appears that the transmission shift lever is either in reverse or second as it is high in view, based on it being a three speed on the column. Yet they are driving at a speed that should be in third, where the lever would be low and not seen.