Unlockable items:
Unlock the following items by performing the corresponding tasks:

ITEM - HOW TO UNLOCK
Bowling Shirt - Import a saved game file from Dead Rising - Case Zero.
Champion's Jacket - Win a TIR Online episode.
Convicts - Kill 10 psychopaths.
Dealer Outfit - Change into all available pieces of clothing.
Hockey Mask - Use every melee weapon to make a kill.
Hunting Jacket - Import a saved game file from Dead Rising - Case Zero.
Overalls - Import a saved game file from Dead Rising - Case Zero.
Tattered Clothes - Kill 1,000 zombies with hand-to-hand.
TIR Helmet - Earn $1,000,000 in TIR Online.
TIR Outfit - Earn $5,000,000 in TIR Online.
Waitress Oufit - Import a saved game file from Dead Rising - Case Zero.
Willamette Mall Outfit - Rescue 50 survivors. (Screenshot 1) (Screenshot 2)

Alternate endings:
Unlock the following alternate endings by performing the corresponding tasks:

ALTERNATE ENDING - HOW TO UNLOCK
Ending A - Complete all cases, give Katey the Zombrex each time, do not give TK the Zombrex before completing "The Facts".
Ending B - Give Katey the Zombrex each time, starting at Case 6-2 allow the time to advance until 7 a.m. on September 29, do not complete "The Facts".
Ending C - Do not do the cases while giving Katey Zombrex each time, be in the safehouse before the military arrives.
Ending D - Be outside the safehouse when the military arrives.
Ending F - Do not give Katey the Zombrex and be in the safehouse by the time the military arrives.
Ending S - Complete all cases, give Katey the Zombrex each time, give TK the Zombrex before completing "The Facts".

Weapons:
Create the following weapons by combining the corresponding weapons:

WEAPON - HOW TO CREATE
Air Horn - Spray paint + Traffic cone
Auger - Pitchfork + Drill motor
Beer Hat - Bottle of beer + Hard hat
Blambow - Bow and arrows + TNT
Blazing Aces - Tennis Racket + Tiki Torch
Blitzkrieg - Assault rifle + Electric wheel chair
Boomstick - Pitchfork + Shotgun
Claws - Boxing gloves + Bowie knife
Defiler - Axe + Sledgehammer
Drill Bucket - Bucket + Drill
Driller - Spear + Power drill
Dynameat - Human hand (or meat) + TNT
Electric Rake - Car battery + Rake
Exsanguinator - Vacuum cleaner + Saw blade
Fire Spitter - Tiki torch + Light machine gun
Flamethrower - Gas can + Super soaker
Flaming Gloves - Boxing gloves + Motor oil
Fountain Lizard - Lizard head mask + Pipe
Freedom Bear - Giant teddy bear + Light machine gun
Freezer Bomb - Extinguisher + Dynamite
Gem Blower - Gems + Leaf blower
Hacker - Computer case + Flashlight
Hail Mary - Football + Grenade
Handy Chipper - Wheelchair + Lawnmower
Heliblade - Toy helicopter + Machete
Holy Arms - Training sword + Nails
Improvised Explosive Device - Box of nails + Gas can
Infernal Arms - Training sword + Motor oil (located behind the casino stage)
Letrci-Rake - Rake + Car battery
Light Sword - Gems + Flashlight
Molotov - Newspaper + Whiskey
Paddle Saw - Kayak paddle + Chainsaw
Parablower - Leaf Blower + Parasol
Plate Launcher - Cement Saw + Plates
Pole Weapon - Push Broom + Machete
Porta Mower - 2x4 + Lawnmower
Power Guitar - Electric Guitar + Amp
Propeller Hat - Serve-Bot head + Propeller
Ripper - Cement Saw + Saw Blade
Roaring Thunder - Goblin Mask + Battery
Rocket Launcher - Pipe + Fireworks
Snowball Cannon - Extinguisher + Super soaker
Spear Launcher - Spear + Leaf Blower
Spiked Bat - Baseball bat + Nails
Sticky Bomb - Lawn Dart + Dynamite
Tenderizers - Box of nails + MMA gloves
Tesla Ball - Hamster ball + Car battery
Wolverine Claws - Boxing gloves + Bowie knife
Zapper - Flashlight + Computer server
Zombie Eater - Push lawnmower + 2X4
Unknown - Leaf blower + Parasol

Additionally you can create the following vehicle-weapon combinations after you unlock the motorcycle trailer by completing the "Here Come The Contestants" mission.

WEAPON - HOW TO CREATE
Chainsaw Motorcycle - Motorcycle + Chainsaw
Machine Gun Motorcycle - Motorcycle + LMG
Rabbit Motorcycle - Motorcycle + Giant Stuffed Rabbit (found outside on top of Moe's Maginations); earns 10 PP for every killed zombie.

Food:
Use the following combinations to create the corresponding food:

Energizer (cannot be injured for ten seconds)
Chili + Chili
Taco + Hamburger

Nectar (attracts nearby Queens and spawns one Queen nearby for six minutes)
Orange Juice + Orange Juice
Jelly Beans + Beer
Onion Rings + Orange Juice

Pain Killer (take half physical damage for one minute)
Beer + Beer
Vodka + Vodka

Quick Step (increase movement speed for one minute)
Milk + Jelly Beans
Wine + Beer
Bacon + Pie

Randomizer (stomach pains that make Chuck vomit three times within three minutes)
Beer + Cooking Oil
Wine + Vodka

Repulse (zombies ignore you for one minute; cancels out Zombait)
Bacon + Chili
Chili + Large Soda
Chili + Ketchup
Chili + Onion Rings
Chili + Pie

Spitfire (spit flames at zombies for one minute)
Bacon + Onion Rings
Ketchup + Ketchup
Bacon + Orange Juice
Chili + Orange Juice

Untouchable (cannot be grabbed by zombies but can still take damage from attacks for one minute)
Bacon + Bacon
Pizza + Large Soda
Bacon + Milk
Chili + Milk
Onion Rings + Milk
Onion Rings + Pie
Pie + Orange Juice
Orange Juice + Milk

Zombait (attract zombies for one minute)
Jelly Beans + Chili
Apple + Taco
Pie + Milk

Free Zombrex locations:
Search the following locations to get free Zombrex.

AREA - LOCATION
Royal Flush Plaza - Found during the case, in Big Roy’s Mart.
Americana Casino - Follow the right side at the fork on the second floor of the BBQ restaurant. Jump on the balcony and over to the closest light then continue across the rest of the lights.
Slot Ranch Casino - Go backstage behind the curtain and climb up the stack of boxes and speakers. Jump on a smaller stack of boxes and speakers.
Underground Access - Go directly under the Atlantica Casino. Note - The underground path overlaps the upper edge of the casino. The Zombrex is near an access ladder on a raised walkway.
Code Blue mission - Save and bring the paramedic to Dean (from the Once Bitten mission). The paramedic will also give Dean a free Zombrex.
Yucatan Casino - Look on top of the tallest slot machine display in the middle.
Royal Flush Plaza - Defeat the Postal Worker during the mission.
Silver Strip Diner - Bring Richard (Hunger Pains) food and rescue him.