When Mac is discussing the human-skin lampshades of Buchenwald, he says that they were made from the tattooed skin of Jews. Most Jews do not have tattoos because of a Biblical prohibition against them. Most of the tattoos for the Buchenwald lampshades instead came from the skin of Gypsies, also imprisoned in the camps with the Jews.
In one scene Sid states that jacketed bullets are designed to penetrate armor. Jacketed bullets are not designed to penetrate armor.