This is a pair of bicycles that were being ridden by puppets at the very beginning of the movie. You see them ride by during one of the pull-back shots of Paris. The two bikes (that appear to be slightly modified toy bikes) are connected together by a metal rod between the red front and yellow back tires. The seats still have support rods in place that would have held the puppets in place as the bikes were pulled across the set.

Screen shot of the puppets riding the bikes down the street.