Sunday Drive (1986)

Two identical cars pull up to a restaurant, one belonging to a childless couple who are taking care of their niece and nephew while their parents are away, who are out on a Sunday drive. The other belonging to a guy who is on his way to meet his fiance and to begin working for her father. In his car is his dog, whom the couple mistake for the children, when they get into his car and drive. While he goes into their car and the children are under a blanket and he mistakenly assumes it's his dog. When they discover the mistake they are both so far away from each other that they don't know what to do.