On Torpedo Run, you can unlock Prof. Gutenburg as a playable character. As soon as the stage starts, fly left over the rocks and you'll see a yellow submarine. If you destroy it, you will get Prof. Gutenburg as a playable character.

Flying through Thugsville, you will eventually come to a harbor area. Immediately after you enter the area, fly out over the water and face the area under the bridge you just came out above. There are 3 ships down there. One of them has a crate on it with the British Flag. Shoot it to get Margaret Basher as a playable Character.

On Monster Isle there is a VERY dense bamboo forest just before the flying green rubber suited monster. There is one very large building in the bamboo with for guns on it. Near the top of the structure, you will see Sammy with a gorilla/wolf/monster (I shot it too fast to see). Shoot the animal and get Sammy Wasabi as a playable character.

Just after starting Bigfoot Mt. there is a building perched on a tall rock with a crane hanging down from it (There are acorns going right through the room(?) it is hoisting. In front of the building on top of the rock, there is a Snowman that looks like Andre. Shoot it and you will find Andre Latoilette trapped inside, unlocking him as a playable character.

Very shortly after the race starts, directly in front of your flyer there is a slightly lighter colored square structure with no roof. A big guy in a black outfit is trying to kill Skeik Abdul with a sword. If you shoot the executioner, you earn Sheik Abdul as a playable character.

In Coyote Canyon, just after the race starts, veer down and to the right and fly down the one street in the small town. At the end of the town is Town Hall, with the big clock. Just to the right of that is a hangman's noose, with Cactus Rose hanging (and struggling to get free) from it. Shoot the gallows to free Cactus Rose and unlock her as a playable character.

On Danger Island. When you get to the jungle area, stay below the trees almost all the way to the left the whole way. You'll see a giant snake wrapped around a guy on a tree branch near the end of the jungle. Just shoot it and you will get Island Jack as a playable character.