Perhaps you should have told that the black star disables you of opening a new parachute. I focused too much on staying airborne that I never noticed collecting the black stars, making me think it was a bug. Just a small tip. ;)
A small tip, either create a menu/title screen or place your plane somewhere visible (thus not behind the health bar). I didn't knew the game has started until the health bar started to drain.
A few sound effects will help too for some enjoyment.
 "Toss the Turtle"){kind=icon}
 "Dino Attack"){kind=icon}
 "UPGRADE COMPLETE!"){kind=icon}
 "Rage 3"){kind=icon}
 "The Base Jumper"){kind=icon}
 "Plane Warfare: Alpha Test!"){kind=icon}