When Potter welcomes Winchester to the 4077, he reads from his file "Harvard Med, Massachusetts General." Later in the Swamp Winchester says he was practically chief of thoracic surgery at Boston General. There is no such hospital in Boston, even though Boston General stands in for the real Mass. General for the rest of the series.
After Winchester completed the heart operation, the doctors are in the scrub room when Radar tells Potter the Burns is on the phone. Moments later, Hawkeye and BJ go to join/listen to the call. However, when the scene switches to Potter's office, Hawkeye and BJ can be seen exiting post-op before entering the office. Post-op is the opposite wing of the building from the scrub room. Hawkeye and BJ would have to pass Potter's office to get to post-op.
When Sgt. Williams of the Military Police is talking to Col. Potter on the phone about the bizarre escapades of Maj. Burns in Seoul, the nameplate on his desk says "SGT WILLIAMS." However, Williams' rank insignia on his sleeve clearly shows that he is a staff sergeant (3 chevrons and 1 rocker), so his nameplate should read "SSGT WILLIAMS."
When Margaret, Hawkeye and BJ are in the Swamp, talking about Margaret's honeymoon, Loretta Swit's fingernails can be seen to be over 1/2 inch long. No nurse, especially a head nurse, would have fingernails that long.
When Major Winchester's Jeep is hit by mortar, it is clearly undamaged, but in the close up, it is on fire. No additional mortar fire is heard or seen after the shot that hits the Jeep.
Col. Potter suggests that Maj. Winchester handle the bowel resection over the protestations of Hawkeye. As chief surgeon Hawkeye has the final decision on patient assignments.
Just before Winchester enters their tent, Hawkeye and B.J. toast actresses Anita Ekberg, Sonja Henie and Ingrid Bergman. Anita Ekberg did not begin acting in movies until 1953 and it is likely that the current episode took place in 1951-1952.
When Winchester is in the Officers Club before he is scheduled to leave he is talking to Igor (played by Jeff Maxwell) but the voice coming out of Igor's mouth is that of Johnny Haymer, who plays Sgt. Zale.
According to Maxwell on the Mash Matters Podcast, the reason for this is that Maxwell was "fired" after filming the scene - for reasons which to this day he claims not to understand.
It's implied that Colonel Potter offers Radar his first cigar. However, in a previous episode ("Chief Surgeon Who?" S1E4), a visiting general walks in and catches Radar smoking Colonel Blake's cigars.
As Winchester formally met Col. Potter for the first time, he should have saluted his new commanding officer. This is the only time in military service when one would render an indoor salute.