Infinite Range Infantry: You are able to fire across the map if you tell your infantry to fire somewhere, and during the wind-up of their attack animation tell them to attack something out of range. This is the easiest on Grenadiers and Tanya.

Formation Exploit: If you add a fast unit into a Ctrl group of slower units such as a mine-layer or transport, you can press the Formation hotkey to make all units move at the same speed as the fastest unit.

If you use the formation exploit with a Ore Truck, it is possible to permanently increase its speed, if the move destination that the Truck goes to happens to be an ore space.

Force-Fire: Despite being unable to see through gap generators, you are still able to force fire through them with aircraft. Some missions utilize this trick in speed running.

Pausing Production: If you build an additional production building, the speed of any units currently building will ONLY build at the faster speed if you pause their production and then resume.