Hawkeye mentions "Mom & Sis" in his letter. Later in the series, his mother died when he was a child and he has no siblings..
In Hawkeye's letter, he talks about his dad being in Vermont. Throughout the majority of the series, Hawkeye states that he has lived in Crabapple Cove, Maine all his life.
The pudding in Margaret's pillow is obviously not yet there when her cot collapses.
The gag candle in Hot Lips' tent becomes much shorter after her cot collapses.
When Hawkeye (dressed as Santa Claus) boards the chopper to take him to the front for emergency field surgery, he takes a medical bag that Henry gave him. But he exits the chopper and descends the rope ladder to the ground without it.
William Katt is credited as "PFC," however, his rank is actually a PV2. A PFC wears a single stripe with a rocker. A PV2 wears a single stripe, as William Katt's character does.
When Henry asks for the football score in the O.R., Trapper tells him, "The Bears beat the Packers, 21 to 10." Those two teams never played a December game, or a game with such a final score, in the years of the Korean War.
Hawkeye is lowered to the wounded soldier by means of a winch mounted on the underside of the helicopter. From his position inside the cockpit, it would be a near impossibility to get himself hooked up to the line and in a position from which he could be lowered.
Hawkeye would be a very inviting and easy target for enemy soldiers as he is being lowered by helicopter to the wounded soldier.
In Korea at Christmas the deciduous trees would be barren. There is green foliage on all the deciduous trees.
After Klinger knocks out Frank, Father Mulcahy calls Klinger, "Goldman".