The four files that the Doctor points to in his laboratory quite clearly read: "Essen Babys", "Dreisehn", "ich Liebe es, Drogen zu tum" and "gross esel, junge dame". Which translated mean: "Eat Babies", "Thirteen", "I love doing drugs" and "Big ass, young lady" (although the German says "donkey" instead of "ass" for the last, and the others are misspelled as well).
The weapons used by the Nazis are all repainted and customized Nerf Blasters. Namely the Maverick, Raider/Rampage and Deploy.
Wilhelm Scream: Heard during the firefight in the opening scene.
When Mengele is showing the team around his lab (at about forty minutes in), he mentions files detailing his work which are briefly shown on screen. In English they are titled; Big Ass Young Lady, Love to Do Drugs, Thirteen, and Eating Babies.