Colonel (actually Lieutenant Colonel) Watson's cap is lacking the gold braid often referred to as scrambled eggs, on the visor. Only lieutenants and captains would wear a cap with a plain black visor.
Although Gomer pronounces the 'corps' in 'Marine Corps' phonetically, i.e., 'corpse,' it's actually pronounced 'core.'
Obvious backdrops outside the barracks.
Sgt. Carter tells the recruits to take their hats off because they're inside, when at the same time he's wearing his hat inside the barracks.
Just after the corporal calls the barracks to attention, a crew member is visible in the lower left next to a bunk.
In a scene that is typically edited out of syndicated reruns, Gomer tells Andy that the Marine recruiter advised that he would be traveling to East Asia while in the Marines. During the Gomer Pyle, USMC series, however, Gomer is never depicted in any such deployment.
Gomer tells Sgt Carter that he doesn't have much of a singing voice. It's already been established that he has a beautiful singing voice.