For the restaurant sequence where McCauley and Hanna finally meet, Michael Mann ran two cameras simultaneously in order to generate a greater level of fluidity between both rivals. Since there were no rehearsals for the scene, this approach afforded both men a more generous margin for improvisational experimentation.
Michael Mann made the movie as tribute to a detective friend of his in Chicago, who obsessively tracked and killed a thief (named Neil McCauley) he had once met under non-violent circumstances.
Heat by michael mann
In 1979, Mann wrote a 180-page draft of Heat. He re-wrote it after making Thief in 1981 hoping to find a director to make it and mentioning it publicly in a promotional interview for his 1983 film The Keep. In the late 1980s, he offered the film to his friend, film director Walter Hill, who turned him down.
Following the success of Miami Vice and Crime Story, Mann was to produce a new crime television show for NBC. He turned the script that would become Heat into a 90-minute pilot for a television series featuring the Los Angeles Police Department Robbery–Homicide division, featuring Scott Plank in the role of Hanna and Alex McArthur playing the character of Neil McCauley, renamed to Patrick McLaren.
The pilot was shot in only nineteen days, atypical for Mann.
he script was abridged down to almost a third of its original length, omitting many subplots that made it into Heat. The network was unhappy with Plank as the lead actor, and asked Mann to recast Hanna's role.