As Samuel Bicke is about to board the plane, an announcement is made that the TWA flight to Atlanta is about to board. On the news, it is announced as him boarding a Delta flight.
Julius Bicke is shown wearing a wedding ring. He is a fervently Orthodox Jew, and such Orthodox males do not wear wedding rings as a matter of religious principle.
From the PA announcement we learn that Bicke will be boarding a TWA flight. In one shot of the aircraft a red pointed cheatline (stripe painted near the windows) is seen which would have been part of TWA's 1972 livery. However, when we see the exterior of the boarding door from the jetway, the Delta Air Lines "widget" (a red triangle and a blue triangle) can be seen.
**Spoiler**
When Sam descends the stairs into the basement, he is clearly and obviously holding a 6-shot revolver. When he shots the dog (presumably), you hear an empty shell casing hit the floor (the ubiquitous sound effect from any movie). As he's holding a revolver and not a semi-auto handgun, there should have been no sound of a shell hitting the floor.
The news on TV first shows the speech of President Richard Nixon answering the House Judiciary Committee Subpoena for Additional Presidential Tape Recordings where he says "the boil must be pricked" from April 29, 1974. Later in the movie the news mentions Robert Preston landing a helicopter on the lawn at the White House the previous evening but that event occurred on February 17, 1974.
A version of the film that was sent to festivals before the visual effects were complete, contains images of aircraft that are not from the story's time period. Shortly after, the visual effects team, digitally removed these logos and added ones from period appropriate airlines.
A version of the film that was sent to festivals before the visual effects were complete contains a scene when Sam is walking to his gate, where both a Southwest Airlines and an America West Airlines aircraft can be seen in the background. America West Airlines did not exist until 1983, and Southwest Airlines did not begin service to BWI until 1993 so the visual effects team, digitally removed the anachronistic logos and swapped them for ones from the time period.
The main hero is taking horizontal elevator at 1:18. This type of moving walkway was first introduced in airports in the mid-1950s and is used to great effect in the opening shots of the 1967 Dustin Hoffman film The Graduate.