MacDonald Avenue in Brooklyn is not in Flatbush.
When BJ and Hawkeye are talking in the shower about Weems, an announcement is made for incoming wounded. Hawkeye tries to quickly wash the soap from his hair, BJ says, 'at least you won't have to scrub." Hawkeye would have to use a much-used towel to dry off, which means he would have to scrub before surgery.
In the opening scene where casualties are being unloaded from the bus, Colonel Potter can be seen in his bathrobe standing still looking to the director for the cue to begin walking toward Hawkeye.
Capt. Rockingham, DDS, thanks Winchester for the use of his oak leaves to pose as a major, but that doesn't explain how he obtained the Judge Advocate branch insignia for his collar, because as a dentist, he would normally wear the caduceus with a "D" -- and certainly nobody at the 4077th would have Judge Advocate insignia for him to borrow.
Dr. Charles Drew did not die of blood loss because he was refused admission to a whites-only hospital. According to a doctor who was in the fatal car accident with Drew, a blood transfusion could have hastened Drew's death had he received one.
Jason Bernard is credited as Major Rockingham when he is, in fact, a captain impersonating a major.