Quoted from Jam_Burglar:

The "hazard value" is the number of points you get for hitting a shot with the flashing orange "hazard" triangles. If you want to raise the hazard value you have to collect "river letters" You can do that by either hitting the bank of blue targets on the left side of the playfied OR by having the "spot river letter" light lit when the ball rolls over the inlane switches (use the flippers to cycle the lights through the in and out lanes). Every time you spell "river" you go up a "river class". River class 1 is 500,000 for each hazard you pick up. River class 2 is 1,000,000 for each hazard, River class 3 is 1,500,000 and so on. You can go up to River Class 6.
Reaching river class 6 is one of the things you need to do to get the "Vacation Jackpot".
The river class resets after each ball making it really hard to reach river class 6. If you hit the "Disaster Drop" ramp 6 times, the game is supposed to "hold bonus" which saves your River Class for the next ball, but that function does not work on L-4. This is why people ususally say its a good idea to upgrade to LH-6.
You get the Camera and Cow by activating the Big Foot Hotfoot. Once that's activated shoot "Bigfoots Bluff". That will spot you the "map" then the "key" (these also help activate the Gold Rush Multiball) but after those the next award is the "Camera" and then the "Cow".
"Spirit of the River" a/k/a "Mystery Canyon" is one of the awards you get for hitting the Whirlpool when the red light above it is activated (the other awards are Ride the Whirlpool, Man Overboard, Lite Extra Ball, etc). If you complete the Bigfoot Hotfoot and get the "Cow" prior to getting awarded the "Spirit of the River" then you'll get the "Secret of the Cow" animation.
Wow, this sounds really freaking complicated as I type this. Pinball! Haha.

Quoted from TheLaw:

I think so...it will say "Welcome to Wet Willy's" and each shot is worth more points and has different animations.