More than 2,000 real-life firefighters showed up at casting in Baltimore, some from as far away as North Carolina. For the filming of the two funeral scenes, more than 800 real-life firefighters and fire trucks from up and down the East Coast, from as far as Massachusetts, made the trek to participate. The website www.firehouse.com coordinated the participation of the firefighters and fire vehicles for those scenes.
Joaquin Phoenix was so afraid of heights before shooting this film that he could not even slide down the 20-foot fire pole. After he finished training he hung off the side of a 20-story building by a single repelling rope.
As part of a preparation for the movie, Joaquin Phoenix trained for a month at a fire academy and spent another month with the men of Baltimore's Truck 10. He became an "honorary member" and had the same tattoo as the men of the company, a bumble bee wearing a fire helmet with an ax.
The filming of the big warehouse scene caused something of a panic in Baltimore. The fire was visible from I-95 and the Baltimore Beltway, so Good Samaritans kept calling the fire department to report it. So many people called that the fire department ended up calling radio stations to confess that the scene was being filmed and to request that people stop tying up the emergency lines.
The scene in which John Travolta talks to Joaquin Phoenix while drinking liquor was improvised by Travolta. The scene originally had Mike Kennedy talking straight to Jack Morrison, but Travolta thought it would be funny to start drinking right in the middle of it.
Joaquin Phoenix was nearly seriously burned in the scene where the factory floor collapses. If you slow down the DVD as he is sliding down the floor you will see a ball of fire caught between the floor and his chest. Luckily the crew awaited him with a fire extinguisher as he fell to pads below.
At the beginning of the film, the Third Alarm assignment to the large warehouse fire was given the location of Newgate and Newkirk Streets, which is the exact location of that very building that was burning.
Every fire scene in the film depicts an actual firefighting incident somewhere in the USA. The scene where Jack Morrison is rescuing the civilian trapped on the 20th story ledge was an incident in New York City, where an acquaintance of Tim Guinee (Tony Corrigan) was rescued by firefighters in the same exact manner.
Stephen Lang was initially a top candidate for the supporting role of Captain, he was in the midst of playing a fire captain in Jim Simpson's "The Guys" in the Flea Theatre. However he lost out once John Travolta expressed interest in the project.
The real Fire Chief (Chief Goodwin) can be seen in some of the scenes in the movie he can be seen dancing with his wife at the wedding reception, standing by Travolta when everyone is singing "Fire," in a funeral scene and in a medals ceremony scene. That station, where the movie starts with Travolta as a captain before he becomes Chief happens to be the station where Goodwin was once a captain himself.