The option of attacking and/or killing not only innocent bystanders, but also police officers. During one segment of the game, Postal Dude must try to exit a meat-packing plant while being attacked by police; it is very difficult to complete this mission without using deadly force against officers.
Al-Qaeda terrorists who carry out a suicide bombing of a church and a marching band (these characters all resemble Osama bin Laden and many characters in the game of Middle Eastern descent are shown to be connected in some way with the terrorists).
The ability to urinate on bystanders to make them vomit in disgust. As cops will eat food items dropped by the player, urinating on a food item that is subsequently eaten by a cop will make the cop regurgitate.
Anthrax-filled cow's heads as weapons which make the victims vomit blood.
The use of cats as silencers for shotguns and machine guns, involving pushing the barrel of the gun into the feline's rectum.
When Postal Dude wears the police outfit and brutalizes innocent people, the other police officers openly admit that they are corrupt. At several points in the game, police NPCs are seen attacking and killing civilians for no apparent reason.
Crack cocaine "health" pipes that can be smoked in order to boost Dude's health to 125, above the usual limit of 100, no matter what value of health the Dude previously had. True to real life, these items will cause the Dude to become addicted, and if another dose is not used while the Dude is complaining about his withdrawal symptoms, his health will eventually be damaged, after which there are no further ill effects (unless another pipe is smoked).
Decapitating people with shovels and kicking the heads about.
Playing "fetch" with dogs using the severed heads of killed NPCs.
Pouring petrol on people and setting them on fire with matches.
Stun gunning people until they cower on the ground and urinate themselves.
A scene that bears resemblance to the Waco Siege of 1993, with a cult group being surrounded by ATF agents at "the compound".
Jihad, the company that makes the goat milk in Monday's chores
Homophobia in the shape of an arcade game prop called "i love you Hunter", as well as a gay dance club location
Racial stereotypes, such as Habib, the owner of the Lucky Ganesh convenience store, who speaks with an stereotypical Indian accent similar of that of Apu from the Simpsons.