Continuity mistake: When Cindy is driving along, singing, both of her windows are rolled down about halfway. We can see the window next to Cindy is rolled down halfway in the first two closeups of Cindy. It then cuts to a wideshot of the car and then another closeup, and the window is now fully winded down. Cindy clearly never winds the window down, it has just rolled down between shots.
Picture added & edited by Hamster