A Plaque for Mayberry - S1-E25
Visible crew/equipment: When Andy and Barney walk into Mayor Pike's office, they stand beside the two women from the Historical Society, and the faint chalk curved marks are visible on the floor where they stand.
A Plaque for Mayberry - S1-E25
Continuity mistake: About 2/5 through the show, Barney comes into the office with a family tree chart. The edge of the paper is on the bottom of the roll sticking out to the left, there's a cut to a different angle and the edge of the paper is on top, not sticking out and still facing to the left. On top, it should be facing to the right.
Continuity mistake: After Frankie pays for the chewing tobacco in the drugstore, in the next closeup of Ellie the cigar box on the shelf behind her has black lines scribbled over all its identifying brand names (which is Van Dyck 43's), but when Frankie walks out the door, in Ellie's next semi-closeup that cigar box is unmarked again.
Continuity mistake: When Barney walks into the chicken coop there's a window on its door, but when Barney hides from Flint there's no such window on its door.
Visible crew/equipment: After Ellie and Andy are turned away by Flint, when they walk back into the courthouse while Barney's lifting the chair, the chalk T-mark is visible on the floor.
Continuity mistake: On Flint's farm there's a cow tied to the back fence, which can be seen in exterior shots throughout the episode - when Ellie, Andy, and Barney are there. After Flint tells Barney to get off his land, in the exterior shot when Barney walks into the barn we see that cow tied to the back fence, but next shot inside the barn we see that very same cow in the stall - note the black/white markings.
Continuity mistake: While Barney's on the farm trying to get Frankie, twice he heads into the barn through the right-side entrance door within the tall sliding double barn doors (about 12 ft high), but when it cuts to the interior shots he's entering through the barn's left-side entrance door, plus the fact that it's not within huge double sliding doors. (This interior set is seen again in "Barney Gets His Man.").
Visible crew/equipment: At the Scobey house, after Ben sits in the unstable chair and it breaks, when Andy and the Scobeys rush over to him we can see the two curved chalk actor's marks on the floor, where Ben had been standing moments before.
Visible crew/equipment: When Barney and Floyd are spying on Sam while he's getting groceries, we can see both of the grocery store's windows and its clear glass, but when Sam drives off the left display window has been covered with a matte dulling spray resulting in an uneven matte surface, to prevent the camera and crew's reflections.
Visible crew/equipment: While waiting for Barney to show up at the surprise party, Opie looks out the window and spots Barney, then when Aunt Bee and Thelma Lou take their places we can see both actors' marks on the floor - the chalk T-mark and the curved chalk mark.
Continuity mistake: After Eddie Brooke offers Barney five dollars and asks to be let go, it cuts to the State Police car passing the "drugs prescriptions" storefront, then Barney and Eddie trip and scuffle for two consecutive shots, and when it cuts back to the State Police car they haven't even passed that storefront yet. Additionally, that storefront is only two stores down from the coffee shop where Barney and Eddie are.
Revealing mistake: During The Manhunt in the woods, Andy, Barney, the trees, etc., cast long shadows due to the overhead sun, but the problem is that we also see Andy's and Barney's shadows being cast in another direction as well, due to the set lighting on location.
Revealing mistake: When Barney and Andy are searching the woods for an escaped con, they stop to rest and you can see the light level of the woods go up and down as the crew tries to adjust the reflector screen for the desired lighting.
Revealing mistake: When Andy tells Opie not to drop by the courthouse anymore after school, in Andy's closeups the shots are flipped - note the part in Andy's hair, the top of his badge, and his backwards buttoned shirt.
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.