While trying to remove the bullet from Hoss's back, the Doctor said that it was too close to his heart and could not do it. They were operating on the right side of his back which is not even close to his heart.
Doctor Mundy refers to Jack the Ripper, but Jack the Ripper was active in 1888 and this episode was set circa the Civil War (1861-1865).
When Ben and Little Joe are speculation of whether Hoss is sick or not; Ben says "if he'd fallen he'd come right through the ceiling and landed right there in the living room". Living room is not a term used in this time period. If a house was big enough to have a room to just sit in, to read, or entertain; it was called a sitting room, or parlor. The term living room didn't come along until the middle twentieth century.