Shooting Fish in a Barrel: CONFIRMED
Even when Adam and Jamie missed the fish, the shockwave from the bullet would kill the fish instantly. The water was pretty much a big conductor, and the shockwave spread through the water, and tripped the meters, meaning the shock was lethal.
Hot Chili Peppers: BUSTED
There is no better cure then milk. The fat in milk lowered down the heat in the chili.
Elephant Myth: CONFIRMED
The mouse actually scared the elephant. Adam and Jamie doughted it, but as soon as the mouse was released, the elephant would have a "scare" reaction and moved away.
Visit Discovery.com/mythbusters for Tori and Grant's Hot Chili Peppers myth at work.