In the scene on the final day where Brennan follows Nixon into the side room, the door is closed, and the Secret Service agent on the right hand side signals two, as in two entered the room. When the camera angle changes to get Frost reaction, the same agent is motioning two again. There would not be a need for the agent to twice motion that two people had entered the room.
In one scene, David Frost tapes a segment with an escape artist in front of the Sydney Opera House, for his Australian talk show. The Quay Grand apartment complex, also known as "The Toaster", is in the background. It was built in 1999.
While Frost and his team are doing research, modern VHS cassettes are visible in one scene. While the VHS format debuted in September 1976, it's extremely unlikely that they would have had VHS tapes of events that happened 2 years earlier.
When Frost is flying from London to New York for the first time in the movie, probably 1976, the external view of the aircraft shows a 747-400 with an extended upper deck. This version of the 747 was not introduced until 1989.
When Nixon arrives for the final interview, he arrives in a single car, not a motorcade, as he did for the other interviews. When Nixon leaves, Frost looks out the window, and you can clearly hear the sound of escort motorcycles, which were not there when Nixon arrived.
Frost and Nixon behave as if they've never met before. In real life, Frost interviewed Nixon when he ran for president in 1968. Nixon enjoyed the interview so much that after he was elected, he met with Frost in the White House to discuss producing a television special.
Upon Frost's first meeting with Nixon at La Casa Pacifica, the former president tells a story about presenting Soviet Premier Brezhnev with a Lincoln Continental. Although Brezhnev was given several American cars as gifts, only one was a Continental. This was given to him in 1973 at Camp David, not La Casa Pacifica.
At the beginning of the film Nixon is shown with Presidential cuff links that are cobalt blue with a gold eagle and stars. Nixon wore an older style of cuff links that had the Presidential seal in color with a white border and a dark blue background. He also wore a tie clasp made this way.
In the opening section, when Frank Langella delivers Nixon's resignation speech, he says "To leave office before my term is completed is abhorrent to every instinct in my body. I have never been a quitter." Nixon actually said "I have never been a quitter. To leave office before my term is completed is abhorrent to every instinct in my body."
After the first interview, Nixon says to Frost "So, eh, day after tomorrow, 10 o clock?", referring to the day and time of the second interview. But, on the day of the second interview, John Birt says to Frost, "So, I had a chance to review yesterday's tapes" and then a few moments later "He was toying with you yesterday, all that shit about Ben Hurr and struggling to raise the money ...". The problem here is that according to Nixon's conversation with Frost the first and second interviews happened with a day in between but according to the conversation between Frost and John they happened on two consecutive days.
When Frost is flying to LAX on a British Airways 747, the flight crew announcements are in a distinctly American accent. While not impossible for British Airways to have American flight deck crew, it would be extremely unlikely.
When Frost and Nixon meet for the first time at La Casa Pacifica, Nixon says, "See you in March," referring to the interviews. Later in the scene Frost writes a $200,000 check to Nixon, and dates it 3/17/75. He could have post-dated the check, to make sure he didn't pay for canceled interviews.
The 747 Frost rides to the USA has a BOAC logo on its tail, but the text on the side clearly says British Airways. British Airways had several 747-100 series aircraft with this hybrid livery (tail numbers G-AWNB, D, E, F, H, I, J and M).
When Frost is reporting on the escape artist, he has a hand mic, but the crew is using a boom mic. Normally, he would have only one mic. However, if Frost needs to move to the shore to talk to the escape artist, the boom might not reach. If he wanted it to look like an "on-the-spot" interview, he would hold a fake hand mic.
Frost's check for Nixon, drawn on the "First Trust Bank of London", is in dollars, not pounds, as one might expect of a British check. However, London and New York (GBP and USD) banking centres enjoy a unique relationship: a USD cheque can be cashed (in either USD, or converted into GBP) in London, and a GBP cheque can be cashed (in either GBP or converted into USD) in New York. A multi-currency account drawn on a London bank can, therefore, be made out in USD.
Following the third disastrous taping session, Frost is meeting with John Birt, Jim Reston and Bob Zelnick around the side of the house. Frost invites them all to a celebratory dinner. Reston asks "what are we celebrating, David? That we're all going to be unemployed?" Frost responds "It's my birthday, Paul." None of the three people he was speaking to were named Paul.
Flipped shot: When Frost pitches his idea to CBS, a poster promoting Hawaii Five-O is on the wall. The poster shows a wave moving from right to left. The image is reversed; commercials and the program's intro show a wave moving from left to right.