Throughout the first five seasons,it appears that Mike and Gloria's bedroom is on the opposite side of the wall from Archie and Edith's bedroom.
But in later episodes both bedrooms appear to be directly across the hall from eachother.
Early episodes made references to Archie's parents having recently visited, or otherwise implied to be still living. As the series progressed, Archie's parents were clearly stated to have both been dead for several years prior to the start of the series. It was the opposite scenario with Edith's parents; the earlier seasons establishing that Edith's father having died before Archie came along, but on season eight's "Two's a Crowd", Archie reminisced to Mike how Mr. Baines told longer stories than Edith, but with bad breath.
In the opening credits, the Bunker house is depicted as having a storm door, but the house in the series does not have one.
In the season 8 episode "Mike's New Job", Mike accepts a position in Los Angeles, and will move out of the house they are renting from the Jeffersons. George then arrives announcing that he has sold the house,
and asks that Mike and Gloria move immediately, However, in the season 9 episode "The Family Next Door", Louise arrives at the Bunkers and tells Edith that they are renting out the house to Ed and Polly Lewis...The same house that they sold the season before.
It's been shown that the Jefferson's house is to the left of the Bunker's from the street's POV. It is also shown that the back door of the Jefferson's house is facing further down the street, while the Bunker's back door faces Irene's house. After the Stivics move next door, they often enter the Bunker's house through their back door. That's definitely the long way around.
The house in the opening credits (that is presumably supposed to be Archie and Edith Bunker's house) does not come anywhere near matching the studio sets that represent the house in the show. For example, window placement and size is completely wrong, and the sets depict the house as having a large front porch whereas, the house in the credits has only a small stoop. Not to mention the house shown in the credits is a duplex; as seen on season three's "Lionel Steps Out", the Bunkers' bedroom window faces the Jeffersons' house, placing all four sides of their interior housing windows (on Lionel Moves into the Neighborhood (1971), the Jefferson's house is shown to be to the left of the Bunker's house from the street's POV).
From the inside, reading backwards, we see "Kelcy's Bar". In most, but not all episodes, the ending credits spell the name of the Brendan Dillon or Bob Hastings character as "Kelsey", not "Kelcy".
Although Archie constantly complains about the crime running rampant in the streets of New York, he's never shown to lock the front door when the family is leaving the house.
Mike is shown being a college student in the 1970s. Assuming that he went to college straight from high school (or even after an open year) he would still be in his early 20s when the series began. Rob Reiner is clearly older than the character would be and he seems to be a very poor student as it takes him nearly six years to complete college (despite going full time) only to obtain a job that would require just a four-year degree.