Other mistake: The safety goggles Barney wears is missing both of its lenses. While it's possible that Barney may wear the goggles just for the look, that possibility is negated when Barney states, "Every piece of equipment and wardrobe has a specific function: helmet - anti-crash; goggles - anti-foreign objects in eyes, that is gravel and/or bugs."
Continuity mistake: When Andy's talking to Gomer through the window while Gomer's holding the pail, in the shots facing Andy the pail's handle is facing out, but in shots facing Gomer the handle is facing the opposite way.
Other mistake: When Barney, Thelma Lou, Helen, and Andy are in the squad car talking about getting dinner, there's black tape on the chrome trim of the triangular vent window - presumably to prevent the camera/crew's reflections; and the vent window is shut in wide shots, but open in the closeup - also to prevent reflections.
Continuity mistake: When Opie shows Andy his arm with the chore list written on it, Andy uses his right hand to hold up Opie's arm, but in the closeup it's Andy's left hand holding up Opie's arm. (00:03:50)
Visible crew/equipment: Barney shows up with the concert sign while Andy's sawing wood, and when he and Andy talk about it, the shadow of the boom pole/mic is moving around on the ground, at the lower left corner of the screen. More of the boom's shadow is visible again, when Gomer shows up and they talk about Goober. (00:14:30)
Revealing mistake: Barney and Mr Weaver scuffle in the dark. When Andy enters the store he turns on the light, but the light switch is still in the off position.
Visible crew/equipment: After Barney brings the "Fun Girls" to Andy's house, when Aunt Bee walks into the parlor there are now three black tape marks visible on the carpet - and those marks weren't there when Barney and the women walked in.
Continuity mistake: At the start, Opie and his friend rush to the front door of the same house to try and sell their products - note the house next door (and the fact that it's three houses down from Andy). The kids then run across the street and have the door slammed in their faces, but then it cuts to the woman next door as she walks to her front door - note the house behind her is that first house Opie went to, even though all the boys just crossed the street a few moments ago.
Visible crew/equipment: At the end, when Barney's talking to all the boys at the courthouse, the camera angle's looking up in Barney's closeups, and the top of the courthouse set is visible right before Barney mentions "intimidation."
Continuity mistake: While Barney and Thelma Lou are stalling Andy and Helen in the squad car, note the long whip antenna is missing (the empty bracket that always holds the antenna in place is over the rear passenger door) when they drive off to Andy's, but when they pull up to the house the antenna's on properly.
Visible crew/equipment: At the courthouse, while Barney and Thelma Lou are trying to stall for time, in the shots facing Andy and Helen when Andy says, "Steaks, chops, macaroni surprise," we can see the shadow of the boom mic moving around at the top, left side of the screen.
A Black Day for Mayberry - S4-E7
Plot hole: About 2/3 through the show Barney is locked inside the armored car and Gomer puts about a gallon of gas into the gun port onto Barney's shoes. After Gomer is told of his error, Barney stays inside the truck. The fumes would have killed him, not to mention the risk of explosion.
A Black Day for Mayberry - S4-E7
Character mistake: When Opie comes in at the beginning of the episode and asks where Andy is, the exchange ends with Barney asking "Something you want to see him about?" and Opie replying "No, I'll wait," which makes no sense in context. It would have made more sense if Barney had asked "Do you want to leave him a message?"
Visible crew/equipment: At the end, when Dr. Breen tells the very tired group, "You all look as serene and relaxed as if you'd just finished listening to a pleasant band concert," in the next shot facing the porch, the shadow of the boom mic is moving around between the two windows above Clara and Andy, at the top of the screen.
Continuity mistake: In earlier episodes, we are told that Gomer can't do mechanic work. He just pumps gas and air: "There's no charge for air; air is free; we don't make no charge for air." But in this episode, Gomer has become an ace master mechanic.
Deliberate mistake: Gomer leaves the woods after they were lost and doesn't have anything with them then when they get to the campsite he has the snare that they made.
Continuity mistake: When Otis makes up a poem about jumping rope, Barney lets go of the rope and Andy is left holding the other end while the rope is left stretched across the floor. One second later when Opie and his friend come running in, Andy is now holding the rope in his other hand all rolled up.
A Black Day for Mayberry - S4-E7
Factual error: An armored truck is going to Fort Knox from Denver would never go through Mayberry. Fort Knox is in Western KY south of Louisville on I-65. NC is accessible mainly by going south down I-75 to Knoxville, then heading South East along I-40 towards Asheville, NC. To get to NC from Fort Knox you would need to go up to Lexington then Knoxville/or go east across the wky fka The Green River pkwy to I-75 then to Asheville. There is no easy route; why would they go through KY to NC and turn back to KY?
My Fair Ernest T. Bass - S4-E17
Character mistake: During the party at Mrs. Wiley's, Ernest Bass' girlfriend is called "Ramona." At the end of the show, Ernest T keeps calling her "Romina".
Barney and the Cave Rescue - S4-E13
Plot hole: Andy and Helen go into the cave and there is a cave in. They find their way out and go into town to change, when they hear on the radio that Barney is getting the townsfolk together to form a rescue, Helen and Andy go back to the cave so barney can rescue them. This makes absolutely no sense. Once they get out of the cave why didn't they go back to tell Barney they were out, why did they have to flag down a truck for the ride back into town? Did they get to the cave with the squad car? It's hard to believe nobody saw them back in town, and how did they get to the cave?
Answer: It was a joke. They were supposed to be dumb hillbillies.
Both. According to later interviews with both Andy and the Dillards band (the real name of the band that played the parts of the Darling children, of which Charlene (Maggie Peterson - Mancuso was also a member) the reason the Darling boys never had any lines was because they would've had to have been paid if they spoke. In return for appearing without lines or pay, Andy promised to get as much of their music onto the show as possible which, he did. This obviously gave them a lot of exposure.