Factual error: In this episode, the regulars receive and respond to letters from a Fourth-Grade class in Hawkeye's home town. Charles receives one from a little girl who says she's sent him a birch leaf. Unfortunately, the leaf he removes from her glassine envelope is a maple leaf. (Note: there was no indication that this was supposed to be her mistake.)
New this month Continuity mistake: After Hawkeye and Trapper finish their toast to the Ritz Brothers, they toss their glasses over they shoulders. Trapper's flips in a lazy arc, and Hawkeye's in a flatter arc. When Radar is at the door, the glasses hit the door at a much higher speed and shatter.
Other mistake: Across the show, several times doctors looking at an x-ray picture say things like, "Looks like he swallowed a whole junkyard" or "His belly is full of shrapnel." In fact, shrapnel, being metal fragments, should show up as clear white spots on the x-ray pictures, but none of that is visible in any of the x-rays shown throughout the show.