Charlie Brown's line "Happiness is a warm Uzi" is a spoof of Peanuts author Charles m. Schulz's famous quote "Happiness is a warm puppy"
When Charlie Brown screams after Snoopy bit off his arm the scream was actually the scream that William Hanna did for Tom in the Tom and Jerry cartoons.
Completely banned in the UK by the BBFC and in Australia by the ACB due to excessive amounts of violence and gore.