In this episode, we get an approximation of Mayberry's population at this point in the show's history when John Masters tells Andy "There's got to be a decent tenor someplace in a town of 2000 people".
In the episode "Hot Rod Otis" Barney and Andy sing a hymn in the jail, oddly enough Barney is in key and sounds good. But in this episode Barney can't carry a tune and he's totally tone deaf.
This episode doesn't mesh very well with Season Two's "Barney and the Choir" where Barney's singing voice was so atrocious and off key Andy and the choir had to go to great lengths to keep Barney's caterwalling voice from being heard at all. Although Ms. Poultice has been working with Barney, it still seems unlikely he would be good enough to actually be singing solos.
It also seems that Andy's reasoning for Barney never being able to sing in the Mayberry Choir again (explained in the epilogue of the aforementioned episode) has been forgotten.
Jim Nabors actually recorded music in real life. He has recorded gospel albums too.
Barbara Griffith, the real-life wife of Andy Griffith at the time, appears in this episode as a member of the choir.
This is the episode in which it is revealed that Gomer - despite his hick speaking voice - has a beautiful singing voice