A good handful of glitches that make this a ten-minute game at most.
1) You can technically select any aircraft from the beginning of the game, even with $0. Simply by clicking multiple times on the plane you want to fly in the aircraft / level select area, you can simply play as that aircraft without buying it. (Using the rocket fuselage and drawing back until your mouse is just above the back of the arrow, you should just launch to the skyscrapers and cause a cascade effect that will net you $4-5MIL with a good collision after each launch.)
2) There's a way (very rare, but it did happen to me once) to glitch into the side of the nuclear plant smokestacks, allowing you to get points almost infinitely until you decide to quit. I managed to get more than $20MIL this way at a rate of about $1M per minute.
3) With the last aircraft, it's possible to perch yourself onto one of the skyscrapers in such a way that it thinks you're still flying, disabling the reset button. It's as rare as the smokestack glitch above, but it's annoying when it does happen.
4) No auto-save means that if you need to reset the game for any reason, all of your progress is reset... not that it matters, though, as explained above.
...so yeah, I can't really justify giving it a score higher than this. Typing this review took as much time as it did to find the glitches I mentioned.