Gomer and the Dragon Lady - S1-E8
Continuity mistake: Sgt. Carter and two buddies are drinking beer in mugs. The "Dragon Lady" flips a man - he hits the table and knocks over a beer bottle and a beer mug on to the floor. When Sgt. Carter and his buddies go back to sit at the table all three beer bottles and mugs with beer are back on the table. (00:06:00 - 00:07:00)
Answer: If you saw the whole series run, you know that Gomer was a country bumpkin. He fumbled, stumbled and tumbled his way into one disaster after another. There was an episode that questioned why he was never promoted. However, a few years before Jim Nabors died, the real Marine Corps, gave him a ceremonial promotion to the rank of Lance Corporal, which Jim gladly accepted.
Unfortunately, I never saw all the episodes. Only a few episodes and a clip of the episode where he sings "The Impossible Dream" which made me wonder why he was still a PFC. Thanks so much for the info.