This article is from the Final-Fantasy and other Square Soft Games FAQ, by email@example.com (Nick Zitzmann) with numerous contributions by others.
Other than the weapons mentioned in the manual, each stage contains at
least one secret weapon. Once a secret weapon has been obtained, it can
be used as initial equipment at the start of each new game.
Juno: The Juno is, basically, a gatling gun. It's more powerful version
of the Vulcan, but has a few hundred less rounds of ammunition. To get
it, you need to activate the three special bonuses on Stage 1. Once the
special bonuses have been achieved, engage the Stage 1 boss. Destroy the
T-shaped thing on its back, and then open fire on the gunpods the boss
occasionally uses. If you're lucky, one of these gunpods will be the
Juno. If not, crash your fighter and try again. Note that the submarine
in level 4 also drops the Juno if you destroy the body before you
destroy the command tower. The final red ship during the final stage
also carries a Juno.
Flash: The Flash is an extremely powerful laser weapon. To get it, you
need to achieve the third special bonus in level 3. If you do it
successfully, a Flash will drop from the ceiling. If not, a Hedgehog
will fall instead.
Mosquito: Mosquitos fire laser-activated homing missiles for when a Wasp
absolutely, positively has to be on time. First, defeat the mini-boss of
stage 4. Get the Spreader from the barrels immediately following the
battle, and immediately go below as many levels as you can. You should
see some barrels behind you. Fire the Spreader backwards to dislodge the
Mosquito inside the barrels.
Python: Pythons fire five straight mines in a row. It can be obtained on
level 5 using a top-mounted Wasp. Near the mini-boss, you'll see a black
Star Wars-style transport in the background - fire Wasps at it to get it
to drop the Python.