The scene at the NBC meeting at Carnegie Hall when Johnny Carson announces his retirement takes place in May 1991. Behind Johnny is the fall 1991 NBC schedule. Mad About You is displayed to air on Wednesday nights. The show did not premiere until the fall of 1992.
When David, Peter Lasally, and Morty head to their CBS press conference, they pass a Radio City Music Hall marquee advertising a show running from September-October. However, the press conference was in January (of 1993).
In an early scene set in 1990, Helen Kushnick and Warren Littlefield are seen talking on carphones about the possibility of Leno being guaranteed the Tonight Show when Carson finally decides to quit. Littlefield is driving a Jeep Grand Cherokee with the ZJ body style, which wasn't introduced until 1993.
When Letterman is doing his show, Robert Morton and Peter Lassally appear in the wings and speak to Letterman. In the next scene, the three are speaking in Letterman's office after the show and Lassally is wearing a different suit.
In a beach scene when David talks to producer and mentor Peter Lassally, a shot of David from behind shows his eyeglass lenses, which are tinted. In other back and front shots of David, his lenses are clear.
The network lineup chart in Littlefield's office shows prime time between 9:00 and 12:00 p.m. Prime time is between 8:00 and 11:00 in the Eastern and Pacific time zones and an hour earlier in the middle of the country.
When David calls Johnny to ask his advice about whether he should take NBC's deal, David says it is a Sunday. But moments before he is watching a football game featuring the Marshall University football team. College teams do not play on Sundays.
When Warren Littlefield (played by Bob Balaban) is thanking the stars of the upcoming fall lineup at an affiliate press conference in May of 1991, he mistakenly thanks the stars "of the 1992 fall line up".
The movie has Rich Little's Johnny Carson wearing a single breasted black blazer and tan slacks for the final "Tonight Show". Carson, for his final "Tonight Show", actually wore a black double breasted blazer and gray slacks.
An early scene takes place at the 1990 Emmy Awards, which were held in September of that year. The next scene is introduced as "Nine months later", which would make it June of 1991. A character looks at a Variety headline that reads May 1991. The next scene is set a week later and shows a character getting out of a cab in New York City. He and all the extras are wearing heavy winter coats indicating the scene is set in a cold month.
A shot of a limousine driving down a NYC street is in fact a shot taken from the 1987 film "The Secret of My Success". Michael J. Fox's plaid shirt is visible through the window as he sits in the driver's side of the limo.