When Barry puts his finger on the glass in the studio and Laura stands up to place her finger against his, the placement of Barry's hand changes dramatically between shots.
Early in the film, Barry expresses anger that his producer isn't putting through more interesting callers. He's supposed to be reading examples from the computer screen that displays a list of callers on hold and the subjects they're calling about, but when we see the screen, some of the callers he says he'd like to talk to aren't listed.
When Dan (Alec Baldwin) and Dietz (John Pankow) are in the control room celebrating the fact that Barry (Eric Bogosian) just agreed to go "national" on air, they are both wearing gray suits. When Dietz goes to a separate room to call the head office (while Barry is talking to the racist caller named Chet), he is wearing a black suit.
When Barry Champlain says that he's going to punish his listeners by playing the Bee Gees' song - Saturday Night Fever, ten times in a row. While they had a monster hit with "Night Fever" there is no such song as "Saturday Night Fever." The record they actually play is Disco Inferno by The Tramps. This may be intentional due to copyright issues; however, the track is on the OST for Saturday Night Fever.
After picking up Ellen from the airport the car that Barry is driving is in "Park." This can be seen in the shots through the windshield.
The first threatening letter addressed to Barry Champlain finishes with the wrongly written sentence: "Your dead" instead of "You're dead".
During the flashback sequence, a Pepsi can with a tapered rim is seen on Jeff Fisher's desk. Dialogue sets the scene during the Carter administration (1977-81), but beverage cans with the tapered design weren't introduced until 1987, around the time the movie was filmed.
The radio station gives its identification as "KGAB in Dallas". Dallas shares its media market with Fort Worth, so all radio and television stations give their identification as being from "Dallas-Fort Worth".
KGAB's radio tower is shown to be in Downtown Dallas. Most radio stations in the Dallas-Fort Worth area are in Cedar Hill, in between Dallas and Fort Worth. While there are exceptions depending on the power of the radio station, if KGAB were as large a station as depicted, its tower would be in Cedar Hill.
When Barry talks about his visit to Germany, he says that he wanted to visit Adolf Hitler's homeland. Hitler was born in Austria.
In two occasions when Barry is taking listeners calls and he's also talking to his producer or bosses, he is not seen pushing the button to direct the call only to his staff which would prevent his radio listeners to hear what's he saying yet they don't hear any of his complaints on the air - only his staff hears his conversation.