When Margaret is in the shower, she has a terrible singing voice, but in previous episodes, she sings very well.
Near the beginning of the episode, Margaret is seen in the OR, but is not wearing sterile gloves, and touches a piece of medical equipment.
When Margaret is trying to talk with Igor in the mess tent, her fingernails are seen as being an inch long. No nurse, especially a head nurse, would have fingernails that long.
While Margaret is singing in the shower, there is an external shot of the shower tent, and there is a clear shot of an open window in the tent. There would not be an open window looking into a shower tent. In the window is an outline of a mannequin or a person wearing white.
The inside of the general's trailer is larger and shaped differently than the outside of the trailer.