In 1989, the film was shown in Russia for the first time. Screenings were low-key, and held at midnight. Still, more than three thousand people attended each showing, with another thousand being turned away at the door. Many of the people had seen the Czech invasion footage before from the Soviet point of view - reedited to show the Soviet invaders as the heroes and the Czechs as the rebels. For many Russians, this was the first time they'd seen the point of view from the other side.
The first cut shown to the studio was under two hours in length and the story was confusing. Philip Kaufman was asked to add in scenes he cut. The next day they were shown the theatrically released version. It's believed Kaufman showed them a shorter and confusing version in order to get his almost three-hour final cut approved with no questions of cutting it.
Jean-Claude Carrière's original script deviated drastically from the final film version. Philip Kaufman feared it was too "arty" for a commercial audience. Milan Kundera read Carrière's original script after seeing the film and said, "That's how it should be done."
Milos Forman personally offered to Philip Kaufman the opportunity to direct the movie after hearing that studios were interested in making a film adaptation of Milan Kundera's successful novel. Forman had to pass the chance to direct it himself because he had family in Czechoslovakia and he feared for them in case of a possible negative reaction from the Soviet government, who were occupying the country at the time.
Several Czechs were in consideration to be involved in this film, including director Milos Forman, but very few ultimately ended up working on the film. Allegedly, protecting relatives still in Czechoslovakia from reprisals from the Communist regime was a primary reason.
The sequence depicting the 1968 Soviet invasion of Czechoslovakia incorporates real documentary footage of the era shot by students of Prague Film School with new scenes recreated for the movie. One of the film students, Jan Nemec, has a small role as a cameraman who is beaten and has his film confiscated by the Soviet police.
Philip Kaufman cast Daniel Day-Lewis after watching glimpses of the actor in a movie showed on TV, which he couldn't remember the name, but he remembered the actor's name and performance and decided he was perfect for the role of Tomas.