The Reunion - S1-E14
Audio problem: When John grabs Olivia from the kitchen sink to rejoin the family (over the washing machine snip) the children's laughter sounds more like a canned echo, or studio audience response.
Character mistake: The NCO in charge of the Navy construction crew is wearing a commissioned officer's eagle insignia on his hat. A non-commissioned officer would have one with a Navy anchor on it. This mistake appears in several episodes showing Ben's Navy service.
Visible crew/equipment: After Muffin spends the night at the Walton house, while she and John-Boy are at the Rockfish bus station, when the bus pulls away the reflections of the camera, crew, and equipment are visible on passenger windows. Also, note, the Newport News bus has license plate number "T-3984" which has been used in previous episodes on other vehicles. (00:19:00)
Visible crew/equipment: At the start, when John-Boy walks into his house with a bag of groceries and the newspaper, just as he says hi to his mother the boom pole and mic are visible at the top, left corner of the screen. (00:01:45)
The Carnival - S1-E3
Factual error: After John-Boy reads the scary bedtime story to Jim-Bob and Elizabeth, when Elizabeth is lying in bed she's holding her Raggedy Ann doll, and in the closeup we can see the doll's Knickerbocker tag. This episode takes place in 1933 (the Chicago World's Fair is mentioned at the end), and the Knickerbocker Toy Company created this doll in the late 1960s. (00:09:30)
Visible crew/equipment: Near the end, when John-Boy thinks he may know where AJ has gone he gets into the vehicle with Martin Walters, then as Todd starts driving away the reflection of a reflector screen becomes visible on the rear window, and it looks like the reflection of the boom operator's raised arm is visible as well. (00:46:40)
Continuity mistake: At the end the narrator states that they never see or hear from A.J. again; however, in Season 4 'The Abdication' is about A.J. coming back in connection with a movie for which he wrote the screen play.
Factual error: Jim Bob is shown communicating with friends in the UK via amateur radio. During WW2 amateur radio operators in most countries were prohibited from transmitting any signals until after the end of the war.
The Secret - S4-E16
Continuity mistake: Jim-Bob's birth certificate reveals he was born January 13, 1923; however in Season 3 The Runaway Jim-Bob says his birthday was June 13, 1924. John-Boy was born just before when John was going off to WWI (1917-1918). If Jim-Bob was born at The Beginning of 1923, that would make him 5 years +/ - younger than John Boy. We know that Ben, Erin, Mary Ellen and Jason are all older than Jim-Bob.
Character mistake: When JimBob is talking to Mr. Perkins in the loft of the barn he mistakenly states that he used to share a bedroom with his 3 brothers when in fact JohnBoy had his own bedroom.
The Attack - S7-E18
Factual error: When Ike is in the hospital and is talking to John, he is wearing a plastic ID wrist bracelet for patients. They didn't start using them until much later.
Continuity mistake: When Ben first sees The Fox in the box trap and rushes over, both the y-branch and straight branch are lying atop the box, but as Ben kneels down now the y-branch is instantly upright with the straight branch still lying beside it, then Ben's siblings run over. (In the next shot, as Mary Ellen mentions Carol Lombarde, the box trap is suddenly set atop two saw horses with the two branches set in their trapping positions. This change is quite abrubt between the two shots and presented as if they have not moved). (00:29:40)
Visible crew/equipment: When we hear Earl Hamner's voiceover at the start, the shadow of the camera crane is moving across the trees, as the camera pans from the Walton house to John at the new mill. (00:01:25)
The Return - S6-E20
Visible crew/equipment: When Hank gives John-Boy a lift home, he opens the rumble seat and places his bags inside. During the drive, a crew member's hat is moving around in the rumble seat area, at both the left and right sides of the screen, particularly the left side. (00:14:00)
The Return - S6-E20
Visible crew/equipment: When John and his son visit Mr. Guthrie at his home, just as Verdie opens the door to the study, behind Mr. Guthrie the black T-mark is visible on the floor at the left side of the screen, where they will all stand shortly. (00:33:00)
Visible crew/equipment: When Erin and Elizabeth help Daisy unpack in their bedroom, just as John-Boy walks into the room, the lighting equipment is visible at the left side of the screen. (00:20:55)
Revealing mistake: While John-Boy is in his old bedroom with John Curtis, having a heart-to-heart conversation with the baby, in all the wideshots from behind the crib the edge of the set is visible at the right side of the screen. (00:21:20)
Visible crew/equipment: When Jason and Verdie go back to the Unwin estate and this time are accompanied by Zeb, they are told that Miss Unwin is at the greenhouse, then just as Jason drives on ahead a few of the crew's modern-day trailers are visible at both the left side and the right side of the screen. (00:39:15)
Visible crew/equipment: When Zeb pulls Esther into the living room with everyone else, Zeb walks over to the small black tape mark on the rug and stands on his mark. Then, as Zeb begins to talk about Erin's entry into the contest, in this wide shot lighting equipment is visible at the right side of the screen. It's visible again when John hugs Erin in the last shot of the scene. (00:25:00)
Factual error: While Jason is practicing piano at the Dew Drop he hears the horn playing outside, then when he walks out of the back door he sees Josh on the trumpet, and in the first shot of Josh we see a blue modern vehicle moving behind the bush, at the top left corner of the screen. (00:05:00)