After the episode where Nellie's restaurant name is changed to 'Caroline's', there are times afterward when the name on the window changes from 'Caroline's' back to 'Nellie's' and back again. Obviously there is stock footage thrown in from time to time.
The time line in Season 1 is not accurate. All the shows preceding the Christmas one (the family's first Christmas in Walnut Grove) would have taken way more than a year to unfold. In particular, Caroline becoming pregnant, going through nine months of pregnancy, and then Baby Charles living a few months before he died, couldn't have all transpired prior to their first Christmas at Plum Creek.
Throughout the seasons, when the Ingalls children are going to and from school, they are inconsistent with the direction of travel. They either come and go over the bridge and pass in front of the saw mill, or come and go on the road that goes behind the saw mill. Also, when leaving the house, they are seen going down the road or over the hill that is across the road.
One of the inconsistencies of the show was its time-line. In the shows first few seasons it would jump back and forth between the the mid 1870s to the early 1880s with little regard for continuity.
In part one of Gold Country, even though there has been continuous torrential rain for months, there is also blazing sunshine and clear blue skies visible in several shots in Walnut Grove, despite the rain.
Featured prominently in at least two episodes ("The Monster of Walnut Grove" and "The Music Box"), restless tree branches are seen and heard immediately outside the front upstairs window, next to the girls' bed. But at no point in the show did any such tree ever exist that close to the house.
There is a quilt that seems to jump from place to place. It is seen everywhere from on the Olsens bed, to Charles' parents bed. It's seen on the bed of others as well throughout the series. It is mostly white with small blocks forming a design similar to the double wedding ring quilt. Other quilts also jump from place to place.
The series often preached "acceptance" and "integration" of the downtrodden and of those who are marginally different than the rest (such as the dwarf, the wild boy etc.) yet those characters who---invariably---would be accepted in the Walnut Grove community, would subsequently never be heard of again, for the rest of the series, as if they'd never existed, let alone moved to Walnut Grove. In a way, this defeated the whole "social tolerance" progressive theme of the series.
In some episodes, when Caroline moves the right way, one can see that she is wearing a bra. The series is set in the 1870s to the 1880s, and bras were not invented until 1912.
The racial and social attitudes on the program reflect its 1970s filming as opposed to its 1880s setting. This is especially noticeable when the series dealt with issues regarding women, minorities and immigrants.
The majority of the men on the series were clean shaven, which not only doesn't match the historical photos of the era, it doesn't match the fashion styles of the time. Few adult men didn't have some form of facial hair and many had full beards.
Despite being prairie women, it's clear, especially during later seasons that all of the female characters have hairdos which were professionally done, as well as manicured nails. Neither of these were "in fashion" for poor women in the 1880's Midwestern US.
Most of the male characters have 1970's style feathered or Afro hair which was not the proper hairstyle of the time of the series.
In part one of 'The Lost Ones' as the train is approaching Charles's wagon blocking the railway line, a large blue truck is clearly visible in a long shot, parked next to the railway.
In "There's No Place Like Home" (Part one) , as the fireworks explode, the shadow of the Steadicam Operator is clearly visible in a tracking shot towards the fire appliance.
None of the areas shown in the television correspond with the range of Midwestern states where the Ingalls lived during Laura's childhood. Most notably many of the areas where they lived were green prairies and rollings tree covered low hills. The series, even the intro, were clearly filmed in an area which experienced an arid climate, likely near and around Central and Southern California.
There is no episode or part of one to show how the blind school Adam, Mary, and Hester Sue ran was taken over by someone else. This, however, will later be spoken about by Hester Sue in "Second Chance."
The real Charles Ingalls had a beard which he wore his entire adult life. Michael Landon, the actor who portrayed him in the series, was always clean shaven or had some slight stubble for the run of the show.