Revealing mistake: After many hours in the OR Hawkeye takes a seat in the wheelchair that Radar's pushing, and when they reach the Swamp there's a wooden ramp on the ground right outside the door, which is never normally there, deliberately placed for this shot so Radar can push the wheelchair into the Swamp.
Revealing mistake: Toward the end of the episode, Henry is talking to a general on the phone when the chopper is coming in. He's trying to tell the man that he can't hear him. As he continues trying to talk, he gives up, and hangs the receiver up on the skeleton's head. If you look, you can see the hook that was conveniently placed for the gag.
Revealing mistake: At the end, in the shot of Klinger singing while he's sewing a dress on his White Rotary sewing machine, as he's guiding the fabric forward it isn't actually under the machine's presser foot, which it needs to be in order to be stitched by the needle.
Revealing mistake: As Henry goes over to the expectant mother, a round takes out the generator. After the lights go out, there is a blue light outside the window, and also blue lights over the action. They can be seen in the reflections on the light sets over the tables.