In 1969 Seberg is depicted driving a yellow Jaguar XKE Series 3 which wasn't in production until 1971.
Jean is seen sitting in the First Class section of a Boeing 747 in 1968 The first commercial flight of the 747 did not take place until 21 January 1970.
Although the characters are shown inside a 747, they deplane from the forward door of an aircraft that is clearly not a 747, as the nose of a 747 has a distinctive "hump."