You can save progress by pressing Select in the map screen.
EXPERT controls has roll and yaw controls, might be more fun.
When your jet crashes, you have to buy a new one if you want to use the same jet again. Alternatively, load your last save.
This game runs at around 30FPS.
Analysis
It seems like missiles are mostly effective against planes when they are flying in the same direction as you. If they are flying perpendicular to your plane, missiles tend to not hit.
Screenshots marked with 🍒 are created by syltefar and are considered public domain, free to use for anything. If you want to, you can note where you found it and link to this page.