Giant ant missions (Counterstrike mission disc)
On the title screen, hold [Left Shift], then use the Left Mouse Button to select the round speaker.
Tesla tanks (Counterstrike mission disc)
Begin a game in skirmish or multi-player mode. Choose to be France and achieve a tech level of 7 or greater. Then, hold [Shift] and click on the radar jammer icon.
Free troops (Counterstrike and The Aftermath mission discs)
Build a missile silo and wait until a missile is ready to be launched. Then, sell the silo and immediately launch the missile. When timed correctly, the sale will be aborted and men will exit the silo.
At the title screen, click on the Westwood logo.