The film is set in December 1973, but two of the obituaries Ralph looks at in the newspaper show the people died in 1974.
After Ralphie loses it about the star falling off their Christmas tree and breaking, he argues with Sandy while she is comforting Julie. Different view angle shows Sandy standing by herself, with Julie nowhere to be seen, three different times.
The eye patch Julie is wearing disappears in one scene and reappears in the next.
The film takes place in 1973, but the former Sears Tower is shown completed in the Chicago skyline. The Sears Tower was completed in 1974.
The December 1973 calendar shown in the opening credits is inaccurate. December 1st 1973 was a Saturday not a Thursday as shown in the movie. Consequently, Christmas day actually fell on a Tuesday not on Sunday as shown in the movie.
The story is set in Indiana in 1973. After Scut Farkus apprehends Ralph he drives Ralph home and his patrol car has blue lights. Indiana police vehicles at that time used all red lights. Blue lights were used by volunteer firefighters.
When Ralphie and his family have the snowball showdown with Black Bart, you can see the string pulling the tumbleweeds. As this is a fantasy sequence, it was intentional for the string to be shown.
The first page of Ralphie's manuscript has a typo: "annial" instead of "annual" (second paragraph)
When Ralphie gets the newspaper out of the mailbox and sees his story, there is a moment when the paper blows toward him and you can see that the back of the page (which should be page 2 of the newspaper) is blank.
The exit sign above the door in Flick's bar is the green European style, not red as it would be in 1970s USA.
The graphics for the Pulitzer ceremony say '74 with an open single quote, as opposed to '74 with an apostrophe. Not only is this wrong, a professional would never mess up that punctuation in 1974.
Ralphie's daughter says she wants the Hungry Hungry Hippos game for Christmas. The movie is set in 1973 and the game wasn't introduced by Hasbro until 1978.
The Palmolive Building is visible in the shot of the Chicago skyline from the north. However, it is missing the Playboy logo that was near the top of the building for decades until the late 1980s.
The cash register seen in the department store when Ralphie is shopping is not accurate to 1973.
Early in the film, Ralph uses the CTA to take the train in Chicago. The sign says 'Redline'. However, the Chicago Transit Authority train system used street names for different train stops until February 21, 1993, when they unveiled new designations that used color-coded train signs and maps for the various routes across the city.
Several cars are not accurate to 1973, such as a parked Chrysler Cordoba introduced in 1975.