I don't remember the Slingblade scene. Here is what Wikipedia says about ingredients in potted meat:
Armour Star: Mechanically separated chicken, beef tripe, water, salt, and less than 2%: mustard, natural flavor, garlic powder, vinegar, dextrose, sodium erythorbate, and sodium nitrite.
Hormel: Beef tripe, mechanically separated chicken, beef hearts, partially defatted cooked beef fatty tissue, meat broth, vinegar, garlic powder, onion powder, salt, flavoring, sugar, and sodium nitrite.
Libby's: Mechanically separated chicken, pork skin, partially defatted cooked pork fatty tissue, partially defatted cooked beef fatty tissue, vinegar, less than 2% of: salt, spices, sugar, flavorings, sodium erythorbate and sodium nitrite.
The defatted beef and pork fatty tissue sounds especially yummy. I haven't had any potted meat since I was a young kid, don't plan to ever eat it again.