The film was made with only technology that was available in the 80's.
Hugh Jackman was invited by the real Gary Hart to stay at his home while the two of them got acquainted. Since Hart's wife was recovering from hip surgery and the two of them were sleeping downstairs, Jackman was actually allowed to stay in the master bedroom and sleep in Hart's own bed.
Bill Burr noted in an interview how convincingly angry Hugh Jackman looked in one particular scene that it he instantly thought he was with Wolverine and initially felt genuine fear. Murphy can be seen dropping his notebook on the ground in response, which wasn't planned in the original script. This candid reaction was left in the final cut.
The real-life Donna Rice (now using Donna Rice Hughes as her married name), the woman with whom Gary Hart was alleged to have had an affair, was given a private screening of the film a few months before its release. (To this day, Hart and Rice Hughes deny they had an affair.) In interviews about the film, Rice Hughes has credited Sara Paxton with an authentic portrayal of her 29-year-old self, has said she appreciates how the film's director and co-writer, Jason Reitman, treated her character with compassion and dignity, and observed that as a 60-year-old grandmother, watching the film moved her to "great compassion" for the 29-year-old person that she was.
Oddly, the film never mentions, shows, or recreates the famous incriminating dock photo of Donna Rice in a mini skirt and sitting on Senator Hart's lap. Though published by the National Enquirer, it was a big nail in Hart's political coffin.