Continuity mistake: Towards the end of the film when "Molly" is chasing Varrick's aircraft, the front fenders of his car have miraculously repaired themselves having been stoved in earlier when he crashed into various other cars in the scrapyard as he first went for the kill.
Continuity mistake: In the scene where the wimpy banker is talking to the boss near the fence, the shadows in the background vary tremendously. They start out as very small, then engulf the entire background. Obviously, hours were spent between takes.
Continuity mistake: In the bank robbery scene, Charley Varrick gets out of the yellow Continental, and closes the front passenger door behind him. In the next shot, the door is open. In the next shot, it's closed again.
Answer: That is a Boeing 'Stearman' biplane.