Kirk Cameron, a Christian evangelist, refuses to kiss any woman other than his wife. To film a scene in which his character in this movie kisses his wife, the filmmakers had to dress Cameron's real-life wife, Chelsea Noble, as the wife character (played throughout the rest of the movie by Erin Bethea) and shoot the kissing scene in shadow so the difference between Noble and Bethea would not be as evident on screen.
For the hot sauce drinking contest it was originally planned to use mouthwash and Gatorade, but it was decided to use something nonpoisonous in case others decided to try it. At first both Caleb and Wayne had just tomato juice, but for each take they added more Tabasco sauce to Wayne's. By the last take, it was pretty much entirely hot sauce. When he said "my mouths on fire" he really meant it, his running off to rinse his mouth was real.
The car used for the car accident had already been wrecked, a different car was used for the earlier scene. They were originally moving it with a wrecker, but they had trouble getting it in place each time, it was falling apart. Soon it was realized that what they really needed was a forklift truck. Amazingly, they found a man who lived right across the track who owned his own forklift. He had seen both of Sherwood's previous movies, and was glad to help out. Producer Stephan Kendrick said "only GOD could make this happen, how many people have a forklift in their backyard?"
Bill Stafford who played Mr. Rudolph is a traveling evangelist who was visiting for a church event. All his scenes were filmed the same day, and it was after Kirk Cameron had left, they never actually saw each other.
In the scene when Caleb is first reading the "love dare" book, there are books on the coffee table. One of those books is "Facing the Giants", which is the novelization of the Kendrick brothers' earlier movie of the same title.
Knowing that this Christian morality tale would be put under a Hollywood microscope, the producers put Kirk Cameron through a strong vetting process, to ensure that no "skeleton in the closet" issues would be discovered. "If you're cheating on your wife or have a problem with drugs or alcohol, they would rather not have you out there on 'The Today Show' promoting the movie," explained Cameron.
Almost all locations used in the film (firehouse, hospital, houses etc.) were existing places that were donated for filming. The only area constructed specifically for the film was the area where Caleb crawls during the house fire, which was not part of the actual house.
The house that was burned was a real one that needed to be removed for development in the area. Shingles and other items had to be removed in order to burn it safely. One of their maintenance people who helped prepare it had actually lived there once, he had grown up in it. Most of the smoke inside the building was digitally added later. Kirk Cameron (Caleb) really did chop the hole through the floor with the ax.
Though Sherwood Pictures produces movies, they are primarily a ministry. For Fireproof, almost everybody involved was a volunteer- over 1,000 people. Every day they began with devotions and a time of prayer. At first a movie on marriage was not what Alex Kendrick was inclined to do, but he felt that GOD was leading him that way. To do a movie, both he, Stephen Kendrick, Jim McBride and Michael Catt all have to be in agreement with it.
During the house fire scene, Kirk Cameron, in a real Albany FD engine, pressed the transmit button on the radio while giving the size-up of the fire. Other Albany FD units began responding, not knowing that it was part of the movie.
The house where Caleb and Catherin live had just been built by Bill Butler who played Neil Prater in Sherwood's previous film "Facing the Giants". The scenes from inside both Caleb and Catherin's parent's houses were also filmed inside this building in different rooms. The outside of Catherin's parents' house was a different building.
The scene right before Catherine (Erin Bethea) goes into the homecare store shows the sign outside of the store. One sign say's 'Bobby Lee Duke's Lollipop Shop'. Bobby Lee Duke was the name of the coach of the Richland Giants in 'Facing the Giants'. The other sign says 'The Biscuit Barn' a restaurant referred to in 'Flywheel'.