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.
Continuity mistake: When Klinger is coming over the hill at the end of the episode, the camera shows him in the outdoor setting, and the spot he's on has sparse vegetation. When the camera goes to a close up of him, the trees and shrubs are thicker and closer to him. This alternates a couple of times.
Other mistake: When Trapper and Hawkeye make the right turn after Trapper tries to use the restroom, you see that Trapper avoids the left side of the road just after the turn. This is to avoid the explosive charge set in the ground used to simulate a mortar round exploding.
Continuity mistake: In the mess tent, Hawkeye is attempting to get the reporter to focus on BJ instead of him by telling the guy about the defibrillator made by BJ to save a life in the O.R. As Hawkeye is making his point, the reporter is putting a sheet of paper into a folder on his typewriter case. After the camera cuts to a close up of the reporter saying his next line, he's putting the paper into the folder again.
Audio problem: When the bulb in the projector goes out, Klinger is trying to fix it. People throw popcorn at him, saying "Find it!" After Potter says "Hit it, Father!", watch Klinger. From the wide shot to the close up, you hear him say "The bulb is hot!", but his lips don't move.